I think I had this wrong at first, so I'd appreciate if you could verify these interactions play out the way I now think they do, or else let me know where I'm getting mixed up if they don't.
1) Zaxara, the Exemplary and Renegade Krasis are both on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which resolves first and enters the field. As the Hydra enters, it triggers the Krasis's evolve ability. The Krasis's ability sees the Hydra as a 3/3, and so evolves the Krasis since its toughness is lower. This is turn triggers the Krasis's 2nd ability and puts another +1/+1 counter on the Hydra. The Stonecoil (finally) resolves and enters the field, which triggers the Krasis's evolve ability, but because the now 4/3 Krasis's ability sees a 3/3 Stonecoil it doesn't evolve the Krasis because neither stat on the Krasis is lower.
2) The same scenario as above, but there is also a Garruk's Uprising on the field under my control. Because the Krasis's second ability would make the Hydra a 4/4 after the token has already hit the field, it's far too late to trigger the Uprising's 3rd ability and I will not draw a card. However, did the Hydra ever have a chance?...Zaxara's ability says it creates a 0/0 hydra, then puts X +1/+1 counters on it, so if instead I cast the Stonecoil for x=4, would the Uprising see a 0/0 hydra enter, or a 4/4 hydra enter?
3) Zaxara, the Exemplary, Renegade Krasis, and Parallel Lives are all on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which Parallel Lives's replacement effect instead makes 2 tokens which will enter at the same time, triggering the Krasis's evolve ability twice. As it resolves, the first copy of the evolve ability on the stack sees a 3/3 hydra, and evolves the Krasis since it's toughness is lower, which in turn triggers the Krasis's second ability and puts a +1/+1 counter on each of the Hydra tokens. The second copy of the evolve ability sees a 4/4 hydra and compares that to the Karsis's now 4/3 stats, and once again evolves the Krasis since it's toughness is lower, which once again triggers the Krasis's second ability and puts a +1/+1 counter on each of the Hydra tokens. Once again, the Stonecoil finally resolves and enters, but doesn't have enough power or toughness to evolve the Krasis.
1) Zaxara, the Exemplary and Renegade Krasis are both on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which resolves first and enters the field. As the Hydra enters, it triggers the Krasis's evolve ability.
No, the 0/0 Hydra entering the battlefield does not trigger that evolve ability.
603.4. A triggered ability may read “When/Whenever/At [trigger event], if [condition], [effect].” When
the trigger event occurs, the ability checks whether the stated condition is true. The ability triggers
only if it is; otherwise it does nothing. If the ability triggers, it checks the stated condition again as it
resolves. If the condition isn’t true at that time, the ability is removed from the stack and does
nothing. Note that this mirrors the check for legal targets. This rule is referred to as the “intervening
‘if’ clause” rule. (The word “if” has only its normal English meaning anywhere else in the text of a
card; this rule only applies to an “if” that immediately follows a trigger condition.)
Example: Felidar Sovereign reads, “At the beginning of your upkeep, if you have 40 or
more life, you win the game.” Its controller’s life total is checked as that player’s upkeep
begins. If that player has 39 or less life, the ability doesn’t trigger at all. If that player has
40 or more life, the ability triggers and goes on the stack. As the ability resolves, that
player’s life total is checked again. If that player has 39 or less life at this time, the ability is
removed from the stack and has no effect. If that player has 40 or more life at this time, the
ability resolves and that player wins the game.
Ikoria: Lair of Behemoths Release Notes
Compiled by Eli Shiffrin, with contributions from Laurie Cheers, Tom Fowler, Carsten Haese, Nathan Long, and Thijs van Ommen
Document last modified April 6, 2020
The Hydra token enters the battlefield as a 0/0 creature. Any abilities that modify or trigger on this event apply. After the token is on the battlefield but before any player can take actions, +1/+1 counters are put onto the token.
The Krasis's ability sees the Hydra as a 3/3, and so evolves the Krasis since its toughness is lower. This is turn triggers the Krasis's 2nd ability and puts another +1/+1 counter on the Hydra. The Stonecoil (finally) resolves and enters the field, which triggers the Krasis's evolve ability, but because the now 4/3 Krasis's ability sees a 3/3 Stonecoil it doesn't evolve the Krasis because neither stat on the Krasis is lower.
The Renegade Krasis is still 3/2, so its evolve ability actually will trigger for the Stonecoil Serpent, meaning a +1/+1 counter for the Renegade Krasis, followed by a fourth one for the Hydra and Stonecoil Serpent
2) The same scenario as above, but there is also a Garruk's Uprising on the field under my control. Because the Krasis's second ability would make the Hydra a 4/4 after the token has already hit the field, it's far too late to trigger the Uprising's 3rd ability and I will not draw a card. However, did the Hydra ever have a chance?...Zaxara's ability says it creates a 0/0 hydra, then puts X +1/+1 counters on it, so if instead I cast the Stonecoil for x=4, would the Uprising see a 0/0 hydra enter, or a 4/4 hydra enter?
A 0/0 hydra entering the battlefield will fail to trigger Garruk's Uprising, just as it failed to trigger evolve. The Stonecoil Serpent entering with the counters will trigger Garruk's Uprising, though.
3) Zaxara, the Exemplary, Renegade Krasis, and Parallel Lives are all on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which Parallel Lives's replacement effect instead makes 2 tokens which will enter at the same time, triggering the Krasis's evolve ability twice.
Got it. I had completely misread those release notes and had a confusion on how intervening if-clause abilities trigger. Thanks!
What about Selvala, Heart of the Wilds as opposed to Garruk's Uprising (and Zaxara, the Exemplary is still on the field)? I've heard that because her 1st ability has the "if" at the end of the ability it doesn't count as an intervening if-clause, so it would trigger for any creatures entering (eg I cast a non-creature x-spell, like Torment of Hailfire, so only a Hydra token would enter the field via Zaxara). Then, so long as by the time the ability resolves the Hydra has large enough power to satisfy the ability, I would draw a card, correct?
Making things a little more complex if the above is true, in the case of a Stonecoil Serpent cast for x larger than any current creature's power, the Stonecoil would enter the battlefield with the same power as the hydra token(s), but after the token(s), so I would not draw a second card since the power has to be greater than each other creature's...but what if The Great Henge was also on the field? Since the Stonecoil entering triggers both Selvala's and the Henge's, abilities at the same time I could choose to sequence them such that Selvala's ability is lower on the stack, the Henge puts the extra +1/+1 token on the Stonecoil, then Selvala's ability would now see a creature with 1 power higher, and I would in fact draw a second card, yes? Lastly, if multiple tokens enter at the same time with the largest power, each would trigger Selvala's ability, but I would not draw a card as each ability would see another creature with equal power?
Got it. I had completely misread those release notes and had a confusion on how intervening if-clause abilities trigger. Thanks!
What about Selvala, Heart of the Wilds as opposed to Garruk's Uprising (and Zaxara, the Exemplary is still on the field)? I've heard that because her 1st ability has the "if" at the end of the ability it doesn't count as an intervening if-clause, so it would trigger for any creatures entering (eg I cast a non-creature x-spell, like Torment of Hailfire, so only a Hydra token would enter the field via Zaxara). Then, so long as by the time the ability resolves the Hydra has large enough power to satisfy the ability, I would draw a card, correct?
That is correct. A triggered ability checks a creature's power when it triggers only if it indicates that in its trigger condition or an intervening "if" clause, which is not the case for Selvala's first ability, especially because an ability of the form "Whenever [something happens], [do something] if [something is true]" does not have an intervening "if" clause (C.R. 603.2, 603.4). (For evolve, see also this thread.) Thus, Selvala's first ability checks the power of creatures when it resolves, not when it triggers or goes on the stack (C.R. 608.2g). Furthermore, if the creature that made that ability trigger is no longer on the battlefield, you use its power at the last moment it was on the battlefield (C.R. 608.2g).
Making things a little more complex if the above is true, in the case of a Stonecoil Serpent cast for x larger than any current creature's power, the Stonecoil would enter the battlefield with the same power as the hydra token(s), but after the token(s), so I would not draw a second card since the power has to be greater than each other creature's...but what if The Great Henge was also on the field? Since the Stonecoil entering triggers both Selvala's and the Henge's, abilities at the same time I could choose to sequence them such that Selvala's ability is lower on the stack, the Henge puts the extra +1/+1 token on the Stonecoil, then Selvala's ability would now see a creature with 1 power higher, and I would in fact draw a second card, yes? Lastly, if multiple tokens enter at the same time with the largest power, each would trigger Selvala's ability, but I would not draw a card as each ability would see another creature with equal power?
1) Zaxara, the Exemplary and Renegade Krasis are both on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which resolves first and enters the field. As the Hydra enters, it triggers the Krasis's evolve ability. The Krasis's ability sees the Hydra as a 3/3, and so evolves the Krasis since its toughness is lower. This is turn triggers the Krasis's 2nd ability and puts another +1/+1 counter on the Hydra. The Stonecoil (finally) resolves and enters the field, which triggers the Krasis's evolve ability, but because the now 4/3 Krasis's ability sees a 3/3 Stonecoil it doesn't evolve the Krasis because neither stat on the Krasis is lower.
2) The same scenario as above, but there is also a Garruk's Uprising on the field under my control. Because the Krasis's second ability would make the Hydra a 4/4 after the token has already hit the field, it's far too late to trigger the Uprising's 3rd ability and I will not draw a card. However, did the Hydra ever have a chance?...Zaxara's ability says it creates a 0/0 hydra, then puts X +1/+1 counters on it, so if instead I cast the Stonecoil for x=4, would the Uprising see a 0/0 hydra enter, or a 4/4 hydra enter?
3) Zaxara, the Exemplary, Renegade Krasis, and Parallel Lives are all on the field under my control. The Krasis currently has its base stats (it's a 3/2 with no counters). I cast Stonecoil Serpent with x=3. On cast, Zaxara creates a Hydra token, which Parallel Lives's replacement effect instead makes 2 tokens which will enter at the same time, triggering the Krasis's evolve ability twice. As it resolves, the first copy of the evolve ability on the stack sees a 3/3 hydra, and evolves the Krasis since it's toughness is lower, which in turn triggers the Krasis's second ability and puts a +1/+1 counter on each of the Hydra tokens. The second copy of the evolve ability sees a 4/4 hydra and compares that to the Karsis's now 4/3 stats, and once again evolves the Krasis since it's toughness is lower, which once again triggers the Krasis's second ability and puts a +1/+1 counter on each of the Hydra tokens. Once again, the Stonecoil finally resolves and enters, but doesn't have enough power or toughness to evolve the Krasis.
No, the 0/0 Hydra entering the battlefield does not trigger that evolve ability.
The Renegade Krasis is still 3/2, so its evolve ability actually will trigger for the Stonecoil Serpent, meaning a +1/+1 counter for the Renegade Krasis, followed by a fourth one for the Hydra and Stonecoil Serpent
A 0/0 hydra entering the battlefield will fail to trigger Garruk's Uprising, just as it failed to trigger evolve. The Stonecoil Serpent entering with the counters will trigger Garruk's Uprising, though.
No, just like the first case.
What about Selvala, Heart of the Wilds as opposed to Garruk's Uprising (and Zaxara, the Exemplary is still on the field)? I've heard that because her 1st ability has the "if" at the end of the ability it doesn't count as an intervening if-clause, so it would trigger for any creatures entering (eg I cast a non-creature x-spell, like Torment of Hailfire, so only a Hydra token would enter the field via Zaxara). Then, so long as by the time the ability resolves the Hydra has large enough power to satisfy the ability, I would draw a card, correct?
Making things a little more complex if the above is true, in the case of a Stonecoil Serpent cast for x larger than any current creature's power, the Stonecoil would enter the battlefield with the same power as the hydra token(s), but after the token(s), so I would not draw a second card since the power has to be greater than each other creature's...but what if The Great Henge was also on the field? Since the Stonecoil entering triggers both Selvala's and the Henge's, abilities at the same time I could choose to sequence them such that Selvala's ability is lower on the stack, the Henge puts the extra +1/+1 token on the Stonecoil, then Selvala's ability would now see a creature with 1 power higher, and I would in fact draw a second card, yes? Lastly, if multiple tokens enter at the same time with the largest power, each would trigger Selvala's ability, but I would not draw a card as each ability would see another creature with equal power?