GigaKnight, what are your thoughts on Soul's Attendant vs Soul Warden? This seems like such a perfect example.
I think the problem you describe is much more prevalent in Magic than in Dominion, simply because in Magic you have a lot more cards out on the field usually, and a lot more triggered effects that could happen. Just this week, someone in my playgroup had a Soul's Attendant out, and didn't gain life when an opponent played a creature (5-player game). By the time it was realized, it was too late, and he couldn't get the life. Had it been a Soul Warden instead, he would have.
Although, this issue arises because of the casual and fast nature of the way people play. The fact is, his Soul's Attendant DID trigger, and it's ability DID go on the stack. That still happens ever though it's "may." Once the ability resolves, at that point he can choose to do it or not. But because we were playing fast and loose, no one ever stopped to say "ok, a creature was just played, now what does the stack look like?" In the same way, in a casual setting, players may play a card or ability, and then another card or ability, without stopping and "passing priority" to the other players.
I guess what I'm saying is in that example, I feel like in a way the group made an illegal play just like we would have if it had been a Soul Warden instead. Because we never actually put the triggered ability on the stack. The guy didn't wait until it resolved and then chose not to gain life. Rather, it never went on the stack, and never resolved, because he forgot to put it on the stack.
Yeah, those cards are a good example; I would go with may.
You raise a very interesting point about the stack in Magic, though. So you're saying you think you'd be required to put the decision itself on the stack with Soul's Attendant? I'm very curious to know what a rules judge would say here. I've never heard of a decision going on the stack, but I haven't played since well before they removed "damage on the stack".
But the fact that they removed "damage on the stack" makes it clear to me that not everything goes on the stack. Is there a clear ruling about what does / doesn't go on the stack? As I think about this more, I'd be surprised if decisions go on the stack. It seems like the stack is place for game events, not meta-events like decisions. So this is what I'd expect: the creature coming into play goes on the stack. When it resolves, if the player opts to gain a life, the life gain goes on the stack. But I could be wrong
I'm pretty sure about this... It's not the decision itself that goes on the stack, but the triggered event does. First a player casts a creature, that goes on the stack. When it resolves, that creature enters the battlefield. At that time, any enter the battlefield triggered events trigger, and go on the stack. This includes ALL things that say "whenever a creature enters the battlefield....". The "may" part of it doesn't come into play yet. At this time in the game, it doesn't event need to be known if the ability says may or not, because the ability hasn't resolved yet. When that ability resolves, you the do what it says, which in this case is "you may gain a life."
As for what goes on the stack, the rules do list for each type of event if it uses the stack or not. Im sure this isn't 100% comprehensive, but I believe spells, triggered abilities, and activated abilities are the only things that use the stack Things that definitely don't use the stack are:
Playing a land
Making a decision (like who to attack with, or whether or not to gain life from Soul's Attendant, after it's triggered ability has resolved)
Paying costs (both paying mana and other costs like tapping a creature or land)
Mana abilities... These are any abilities that do not have a target, and can add 1 or more mana to your mana pool.. I.E. a Forrest's activated ability of adding a green mana to your mana pool.
Dealing damage
Any state-based effects (like losing the game for having 0 or less life)