I attack my opponent with Butcher of Malakir and 2 1/1 Vampire Tokens. My opponent blocks one of the Vampire Tokens with Apex Altisaur. After the token dies and Butcher of Malakir's sacrifice ability triggers and is put on the stack, can my opponent use Strionic Resonator to copy Altisaur's Enrage again to put in on top of the stack over the sacrifice ability to fight my other token?
Yes. That ability would still be on the stack, and therefore be a legal target for resonator. Any new object on the stack is going to resolve first, so your opponent can have Altisaur fight something else before the sacrifice trigger resolves.
Note, that Strionic Resonator is not necessary to kill of your two other creatures. Due to APNAP order and you being the active player, your sacrifice trigger is below the enrage trigger. Your opponent can target either of your two creatures with it, and when it resolves, there are again your sacrifice trigger and the enrage trigger which go on the stack yet again in APNAP order. So now there are two of your sacrifice triggers on the stack below an enrage trigger, which your opponent can use to target and kill your last creature, all before he has to sacrifice anything. (Optimally, your opponent would kill your Butcher with the first enrage trigger, so that there is no third sacrifice trigger for the last token.)
Former Rules Advisor
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