Assuming neither Mazirek nor Turntimber Sower was sacrificed this way:
As part of activating an ability (other than a mana ability [C.R. 605.3b]), you put that ability on the stack before paying its costs (C.R. 602.2a-b, 601.2h). If a triggered ability (such as found in Mazirek or Turntimber Sower) triggers as you pay those costs, the triggered ability will go on the stack above that activated ability (C.R. 405.2) and get to resolve before it (C.R. 117.4). If multiple triggered abilities you control would go on the stack this way at the same time, you choose their order (C.R. 603.3b).
In this case, the "you" on Sword of Hearth and Home's second ability means the player who controlled that Equipment when the ability triggered.
Gaining control of a permanent doesn't change control of any Auras or Equipment attached to that permanent. An Aura's or Equipment's "controller is separate from the [enchanted or equipped permanent's] controller ...; the two need not be the same" (C.R. 301.5d, 303.4e).
The following explains what "you" or "your" means on any permanent's ability, including an Aura's or Equipment's ability or an ability granted to that permanent:
On a static ability, this is the permanent's controller (C.R. 109.5).
On a triggered ability, this is the player who controlled the permanent when the ability triggered (C.R. 109.5). It's that player who follows the ability's instructions (C.R. 113.8, 608.2c).
On an activated ability, this is the player who activated that ability (C.R. 109.5). In general, only the permanent's controller can activate the ability (C.R. 602.2).
Usually, Den Protector is not a "transforming permanent" under C.R. 707.8a, that is, a transforming double-faced permanent or a transforming token, so a token that's a copy of Den Protector will not be a transforming token and will have Den Protector's copiable values (which is 2/2 creature by default if Den Protector is face down and was cast via megamorph) (C.R. 708.2, 702.37b).
In general, while a player casts a spell or activates an ability, no player has priority, so no other player can cast spells or activate abilities (including those that would keep costs from being paid) (C.R. 601.2a-i and 602.2a-b have no priority window until the spell is cast or ability activated; C.R. 117.1a-b). In general, after a player announces a spell, the next time a player can get priority is only after that spell finishes being cast (C.R. 601.2i; C.R. 117.1a-b).
In general, an ability that triggers goes on the stack, even if it contains "you may" in its text (C.R. 603.5). If the ability requires targets, choosing the required number of them is not optional, even if the ability contains "you may" in its text (an example is Conclave Naturalists) (C.R. 603.5, 603.3d, 601.2c).
In both cases, the choice to search the library or draw a card, respectively, is made when the ability resolves, not when it triggers or goes on the stack (C.R. 603.5, 608.2d).
If the first and second modes of Rankle and Torbran's last ability were chosen, you can sacrifice the Treasure token you just created if it's somehow a creature, even if it has toughness 0 or less.
In general, state-based actions (including the one that sends creatures to the graveyard for toughness reasons) don't happen while a spell or ability is resolving (C.R. 704.4, 117.2e, 704.5f).
Tribute to the World Tree's ability checks the creature's power when it resolves, not when it triggers or goes on the stack (C.R. 603.8h). Thus, the ability will trigger if "a creature enters the battlefield under your control", regardless of its power. The ability doesn't say, "...under your control, if its power is 3 or greater, draw..." (review C.R. 603.4).
Also, compare Tribute to the World Tree with Elemental Bond.
Also, note that Mistcutter Hydra's last ability is not a triggered ability. An ability that starts with "when", "at", or "whenever" is a triggered ability (C.R. 603.1). An ability that starts with "As", "If", "You may have", or "[Something] enters the battlefield" is not a triggered ability.
Neera's ability lets you cast a certain kind of spell but not as a continuous effect (e.g., "this turn", "for as long as...", "during any turn..."), so you cast it this way while that ability is resolving, which is a moment that spells normally can't be cast, not even instant spells (C.R. 608.2g, 117.1a). This is a one-shot effect (C.R. 610.1).
The ability doesn't "ignore" any "timing restrictions". But in general, a card's type, such as instant or sorcery, doesn't impose a restriction on when a player can cast a spell (review C.R. 117.1a); examples of timing restrictions include those found in Aleatory, Savage Beating, or Teferi, Mage of Zhalfir.
Note that the comprehensive rules never speak of "speed" with respect to sorcery or instant spells.
If I have three creatures in play including Syr Faren, the Hengehammer and I plan to attack with all three, do I have to declare which one of the other two creatures will receive Syr's +X/+X upon declaring attack or can I wait to see which creatures my opponent blocks?
A target is chosen for Syr Faren's ability when the ability goes on the stack (C.R. 603.3d, 601.2c).
In this case, if Syr Faren's ability triggers, it will go on the stack almost immediately afterward, during the declare attackers step (C.R. 508.2, 117.5).
EDIT (Mar. 24): Clarification.
If I wanted to cast giant growth on Syr to give one of my other attacking creatures the additional +X/+X, would I have to cast Giant Growth on Syr before declaring attackers?
The ability checks Syr Faren's power when the ability resolves, not when it triggers or goes on the stack, since the value of X is not needed in order to put the ability on the stack (C.R. 608.2h, 603.3d, 601.2b). You can cast spells, such as Giant Growth, in response to that ability (C.R. 117.1a, 117.7). Compare Syr Faren with Necrologia, Aether Burst, Reap, or Custodi Soulcaller's or Spellstutter Sprite's last ability (C.R. 108.1).
In general, a creature doesn't enter the battlefield blocking anything, even if it enters during the declare blockers step. Thus, a token created with Triplicate Titan doesn't enter the battlefield blocking anything, even if Triplicate Titan died while blocking something, because Triplicate Titan doesn't say so.
However, your opponent can activate Osgir's second ability, sacrificing Triplicate Titan, after attackers are declared and before blockers are declared. Then, in general, the tokens will be available to block by the time the declare blockers step starts.
If X is 4, Hungering Hydra will cost {4}{G}, despite Goreclaw.
For purposes of Goreclaw, Hungering Hydra on the stack has power 0 regardless of the value of X for it. Hungering Hydra is given counters due to its first ability only as it enters the battlefield, and not while it's being cast.
However, the value of X will affect Hungering Hydra's mana value on the stack (C.R. 202.3e); compare Goreclaw with Krosan Drover.
Barkhide Troll's first ability gives Barkhide Troll +1/+1 counters upon entering the battlefield, so that the creature is 3/3 from the first moment it's on the battlefield (C.R. 614.1c, 614.1d). Barkhide Troll doesn't enter as 2/2 and then become 3/3 (C.R. 603.6b).
Note that Barkhide Troll's first ability is not a triggered ability. An ability that starts with "when", "at", or "whenever" is a triggered ability (C.R. 603.1). An ability that starts with "As", "If", "You may have", or "[Something] enters the battlefield" is not a triggered ability.
Fireball deals all the damage to its targets at the same time (it uses the action verb "deals" only once) (C.R. 608.2c, 608.2f). Thus, a single prevention effect from Circle of Protection: Red can prevent all of that damage (see also C.R. 700.1).
(Of course, Fireball or any other spell can have only a finite number of targets.)
A spell can gain blitz due to Henzie even if it already has blitz. In general, an object can have multiple instances of the same ability, and each works separately (C.R. 113.2c).
As part of activating an ability (other than a mana ability [C.R. 605.3b]), you put that ability on the stack before paying its costs (C.R. 602.2a-b, 601.2h). If a triggered ability (such as found in Mazirek or Turntimber Sower) triggers as you pay those costs, the triggered ability will go on the stack above that activated ability (C.R. 405.2) and get to resolve before it (C.R. 117.4). If multiple triggered abilities you control would go on the stack this way at the same time, you choose their order (C.R. 603.3b).
Gaining control of a permanent doesn't change control of any Auras or Equipment attached to that permanent. An Aura's or Equipment's "controller is separate from the [enchanted or equipped permanent's] controller ...; the two need not be the same" (C.R. 301.5d, 303.4e).
The following explains what "you" or "your" means on any permanent's ability, including an Aura's or Equipment's ability or an ability granted to that permanent:
See also:
- https://www.reddit.com/r/mtgrules/comments/10j5780/if_i_steal_a_creature_do_i_also_steal_their/
- https://www.reddit.com/r/mtgrules/comments/10pfeav/modify_rules_and_shifting_control/
- https://www.reddit.com/r/mtgrules/comments/m4yee1/when_you_hijack_a_creature_spell_does_it_also/
- https://www.reddit.com/r/mtgrules/comments/xz5iff/kharn_the_betrayer_rules_questions/
- https://www.reddit.com/r/mtgrules/comments/yjzgzy/kharn_the_betrayer_and_basilisk_collar/
- https://www.mtgsalvation.com/forums/magic-fundamentals/magic-rulings/813617-unholy-indenture-v-change-of-control
- https://www.mtgsalvation.com/forums/magic-fundamentals/magic-rulings/818516-stolen-legendary-permanent
See also:
- https://www.reddit.com/r/mtgrules/comments/ms6o0h/hi_been_playing_for_a_little_while_and_ive
- https://www.reddit.com/r/mtgrules/comments/muxo78/tap_my_opponents_mana_after_he_declared_his_move/
In general, state-based actions (including the one that sends creatures to the graveyard for toughness reasons) don't happen while a spell or ability is resolving (C.R. 704.4, 117.2e, 704.5f).
Also, compare Tribute to the World Tree with Elemental Bond.
Also, note that Mistcutter Hydra's last ability is not a triggered ability. An ability that starts with "when", "at", or "whenever" is a triggered ability (C.R. 603.1). An ability that starts with "As", "If", "You may have", or "[Something] enters the battlefield" is not a triggered ability.
The ability doesn't "ignore" any "timing restrictions". But in general, a card's type, such as instant or sorcery, doesn't impose a restriction on when a player can cast a spell (review C.R. 117.1a); examples of timing restrictions include those found in Aleatory, Savage Beating, or Teferi, Mage of Zhalfir.
Note that the comprehensive rules never speak of "speed" with respect to sorcery or instant spells.
See also the following:
- https://www.reddit.com/r/mtgrules/comments/11fn9xr/timings_with_zethi/
- https://www.reddit.com/r/mtgrules/comments/108ktl9/specific_questions_re_oskars_timing_restrictions/
- https://www.reddit.com/r/mtgrules/comments/zvig7i/question_about_suspend/
* https://www.mtgsalvation.com/forums/magic-fundamentals/magic-rulings/817402-timing-rules-are-weird
* https://www.mtgsalvation.com/forums/magic-fundamentals/magic-rulings/754724-is-there-an-official-ruling
A target is chosen for Syr Faren's ability when the ability goes on the stack (C.R. 603.3d, 601.2c).
In this case, if Syr Faren's ability triggers, it will go on the stack almost immediately afterward, during the declare attackers step (C.R. 508.2, 117.5).
EDIT (Mar. 24): Clarification.
The ability checks Syr Faren's power when the ability resolves, not when it triggers or goes on the stack, since the value of X is not needed in order to put the ability on the stack (C.R. 608.2h, 603.3d, 601.2b). You can cast spells, such as Giant Growth, in response to that ability (C.R. 117.1a, 117.7). Compare Syr Faren with Necrologia, Aether Burst, Reap, or Custodi Soulcaller's or Spellstutter Sprite's last ability (C.R. 108.1).
See also:
- https://www.reddit.com/r/mtgrules/comments/11dg2bg/otharri_angelic_exaltation/
- https://www.reddit.com/r/mtgrules/comments/q4gugo/when_a_spell_or_ability_checks_the_state_of_the/
- https://www.reddit.com/r/mtgrules/comments/vtq3xm/x_with_traverse_the_outlands/
- https://www.reddit.com/r/mtgrules/comments/rmmbng/halana_alana_and_reckless_stormseeker/
Compare Triplicate Titan with Brimaz, King of Oreskos or Flash Foliage.
However, your opponent can activate Osgir's second ability, sacrificing Triplicate Titan, after attackers are declared and before blockers are declared. Then, in general, the tokens will be available to block by the time the declare blockers step starts.
EDIT: Clarification after comment 4 was posted.
For purposes of Goreclaw, Hungering Hydra on the stack has power 0 regardless of the value of X for it. Hungering Hydra is given counters due to its first ability only as it enters the battlefield, and not while it's being cast.
However, the value of X will affect Hungering Hydra's mana value on the stack (C.R. 202.3e); compare Goreclaw with Krosan Drover.
Note that Barkhide Troll's first ability is not a triggered ability. An ability that starts with "when", "at", or "whenever" is a triggered ability (C.R. 603.1). An ability that starts with "As", "If", "You may have", or "[Something] enters the battlefield" is not a triggered ability.
(Of course, Fireball or any other spell can have only a finite number of targets.)
See also:
- https://www.reddit.com/r/mtgrules/comments/u7o3jk/henzie_and_wave_of_rats/