Not at any point, no. When your commander moves to your graveyard, you get one occasion to put it in the command zone immediately as a state-based action, but if you opt not to do it at that point and leave your commander there, it stays there until some cost or effect tries to move it from the graveyard. If an effect exiles it from your graveyard, for example, then you'll get an occasion to put it in the command zone from exile, and if something tries to put it in your library, you can put it in the command zone instead as a replacement effect. But you can't just put it in the command zone at will.
It depends on the wording of the triggered ability. Drivnod will double Nadier's Nightblade's ability if a creature token you control dies, because in this case the trigger event of the Nightblade's ability is in fact a creature you control dying (i.e. moving from the battlefield to the graveyard). But it will never work with Mirkwood Bats, because their trigger event is not the move from battlefield to graveyard, but the sacrifice action, which generally causes dying but is not that in-and-of itself. Sacrifice is a keyword action, and that action itself is the trigger event, so it doesn't qualify for Drivnod.
From Drivnod's Gatherer notes:
04/02/2023 An ability that triggers when a creature "leaves the battlefield" will trigger twice if that creature leaves the battlefield by dying.
04/02/2023 An ability that triggers on an event that causes a creature to die doesn't trigger twice. For example, an ability that triggers "whenever you sacrifice a creature" triggers only once.
Ah, hmm, this looks a lot more specific than I remember (but I've been away from mtg for many years). Is there no general "if the game asks for a single value, but finds multiples, it adds them" rule?
(And whereas if it checks for equality against a single number, it checks each one it receives)
Not really, no. These things are treated on a more specific basis. Got another case in mind not involving mana value?
Would someone be able to point me to this section of the rules? I'm think e.g. of when a card's CMC is asked for or checked, but it turns out to be a split card.
There you go:
202.3d. The mana value of a split card not on the stack or of a fused split spell on the stack is determined from the combined mana costs of its halves. Otherwise, while a split card is on the stack, the mana value of the spell is determined by the mana cost of the half that was chosen to be cast. See rule 709, "Split Cards."
Players gain priority to interrupt the stack after each spell (or ability) resolves if they want to add to the stack. The active player (the player whose turn it is) gains priority first. Once they pass, the remaining players gain priority in turn order. Note that a player whose turn it is may respond to their own spell or ability immediately by stating "hold priority" so that others don't respond prematurely by assuming they're passing priority. Also note that if a spell on the stack has Split Second, players can't cast spells or activate abilities, but triggered abilities and copies of spells may still be added to the stack. For more info, see Rule 117
A small correction: a player gets priority first after casting a spell or activating an ability of theirs, or after taking a special action (e.g. turning a face-down creature face up with Morph or Disguise), no matter whose turn it is, then other players get priority in turn order. The active player gets priority first in every other situation.
117.3c. If a player has priority when they cast a spell, activate an ability, or take a special action, that player receives priority afterward.
Unfortunately, such "wonky combos" with different permanents with abilities that exile cards and other abilities that do something with those exiled cards don't work, because of the "linked abilities" rules. Helvault's last ability, for example, can only return cards exiled specifically by one of its own two other abilities.
607.1. An object may have two abilities printed on it such that one of them causes actions to be taken or objects or players to be affected and the other one directly refers to those actions, objects, or players. If so, these two abilities are linked: the second refers only to actions that were taken or objects or players that were affected by the first, and not by any other ability.
607.2a. If an object has an activated or triggered ability printed on it that instructs a player to exile one or more cards and an ability printed on it that refers either to "the exiled cards" or to cards "exiled with [this object]," these abilities are linked. The second ability refers only to cards in the exile zone that were put there as a result of an instruction to exile them in the first ability.
So, if I understand correctly, in a situation where I had Teysa Karlov on the board, I would get double everything except for Village Rites, where I would only get the standard two cards. But what about if instead of Village Rites, I used the sorcery option Promise of Aclazotz? Would I still only get one demon from it? And could the enchantment option potentially give me two copies of the token creator?
There's no additional interaction with Promise of Aclazotz/Foul Rebirth either. What Drivnod and Teysa are looking for are triggered abilities which trigger event is a creature being put in the graveyard from the battlefield, and there is no such ability here. Promise of Aclazotz (the enchantment part) has a triggered ability, but its trigger event is simply "at the beginning of your end step", and Foul Rebirth (the sorcery) doesn't use a triggered ability as part of its effect. The "if you do" clause is not a triggered ability, it's simply a part of the spell's effect that you carry out as it resolves. Also, Teysa and Drivnod don't work with abilities which trigger event is specifically a sacrifice, worded "whenever you sacrifice a creature" or the like, because the trigger event is doing the sacrifice keyword action, and not actually the creature going to the graveyard. Such abilities have the advantage of triggering even if there is a Rest in Peace on the battlefield, for example, but Teysa and Drivnod don't see them.
In a typical game of Magic, during the first player's turn they are not allowed to attack or draw. Now for Commander/EDH, specifically a game of 3+ players, is the first player allowed to draw and who is allowed to attack first at their earliest opportunity? I know that's not normal but there are cards that have haste and can be cast on turn one for early damage. (I know that typically we give every player a turn one draw but I would like to confirm.)
The starting player skipping the draw step of their first turn is a duel and two-headed giant-specific rule. It doesn't apply in multiplayer free-for-all (which most Commander games are), even the starting player draws a card during their first draw step. As for attacking, being on the first turn of the game doesn't change anything, if your creature has haste it can attack the turn it enters, otherwise it needs you to begin a turn with it already under your control.
Hullbreaker Horror has a modal ability, denoted by the wording "choose one". Spellskite can't change modes, only targets, so it won't be able to change the target, because it's not itself a legal target for the ability which on that mode can only target spells. However, Spellskite could redirect something like Divide by Zero cast on a spell, because that's not modal.
Reducing toughness and dealing damage are two completely different things. Skullclamp reduces toughness, it doesn't deal damage. The only things that cause damage to be dealt are attacking and blocking creatures during the combat damage step of the combat phase, and spells and abilities that deal damage or make something else deal damage, which will always use the word 'damage'. Also note that damage usually doesn't reduce toughness (barring things like wither or infect that modify the results of damage), rather it stays marked on creatures until end of turn and it causes them to be destroyed if it equals or exceeds their toughness. So one can combine damage and toughness reduction to destroy a creature (reducing toughness making it so it requires less damage to be destroyed), but they're not the same.
As a sidenote, a creature can of course also die from having its toughness truly reduced to 0 (which is what happens when you equip Skulllclamp to a 1-toughness creature to immediately draw cards), but this is not being destroyed. That gets around indestructible, but combining some toughness reduction with damage doesn't.
I know I went beyond your question, but while we're explaining the distinction, might as well cover it all.
Provided you have a way to get around the fact that Lara Croft is legendary of course, well, each Lara's attack trigger resolves separately, and each gives you a separate permission to play an exiled card with a discovery counter on it this turn. Those permissions are cumulative, if you had 3 Lara attack triggers resolve, you can play 3 of those cards.
All of that is possible without issue. If you sacrifice a Flinger after its ability has triggered, the ability still resolves fully and the Flinger will be able to deal damage even if it's not on the battlefield anymore. So you can sacrifice the two Flingers to each other and both will work. The second scenario with another creature also works fine.
This particular forum is meant exclusively for rules questions. You'll have to ask elsewhere for card suggestions, like our Commander forums. I'll lock this thread to avoid a stratregy disucssion starting.
No, you can't. If you have Ruby Medallion out, unless something else is affecting Sundering Stroke's cost, it costs 5R and you can't spend more than 6 mana to pay that.
You don't really seem to be asking a rules question here, so I'm not sure how much we can help... All I can tell you is that I do believe that Interdict's functionality was indeed affected by the Sixth Edition rules in the way you describe. As for why WotC didn't errata the card, I'd say that's because they don't always go out of their way to perfectly restore previous functionality of old cards, and there are some fixes they deem would be "going too far". But this isn't the place to debate this, and we can't help you bring about the change you'd like, we're not WotC. You could bring up the issue to the rules manager Jess Dunks, if you're so inclined.
From Drivnod's Gatherer notes:
As a sidenote, a creature can of course also die from having its toughness truly reduced to 0 (which is what happens when you equip Skulllclamp to a 1-toughness creature to immediately draw cards), but this is not being destroyed. That gets around indestructible, but combining some toughness reduction with damage doesn't.
I know I went beyond your question, but while we're explaining the distinction, might as well cover it all.