"May" clauses and targeting
Put shortly: I have a board of only [[Soulherder]] and [[Phantasmal Dragon]].
At the end of my turn, do I have to sacrifice the dragon?
Bonus question: How would it have to be phrased to work the opposite way?
Posted Jun 19, 2019, 11:11 PM UTC · edited
Yes. "May" abilities still have their target selected when the ability goes on the stack - it's not until you go to resolve the ability that you choose. In this case, the dragon is not there anymore because you had to sacrifice it.
114.1: Some spells and abilities require their controller to choose one or more targets for them. The targets are object(s) and/or player(s) the spell or ability will affect. These targets are declared as part of the process of putting the spell or ability on the stack. The targets can't be changed except by another spell or ability that explicitly says it can do so.
603.5: Some triggered abilities' effects are optional (they contain "may," as in "At the beginning of your upkeep, you may draw a card"). These abilities go on the stack when they trigger, regardless of whether their controller intends to exercise the ability's option or not. The choice is made when the ability resolves. Likewise, triggered abilities that have an effect "unless" something is true or a player chooses to do something will go on the stack normally; the "unless" part of the ability is dealt with when the ability resolves.
I've seen responses suggesting either outcome, but this one is longer and quotes the official rules, so im guessing it is correct
Thanks!