Quote from JaishivaJai »
I don't have Eidolon of the Great Revels yet, but I'm curious about an interaction between Collateral and this card. Imagine this: We have Eidolon out with collateral in hand plus red mana open. Opponent targets Eidolon for removal, triggering it's ability. We respond with collateral sacrificing Eidolon. It seems to me that we evade triggering Eidolon ourselves in this instance. In my mind, the spell isn't cast until the creature is sacrificed, thus it's ability won't trigger when Collateral is cast because Eidolon isn't on the field anymore. Any rules expert have a definitive answer to this?
If this is true, there's further potential for this, in a mirror match up for instance. Imagine having Eidolon out, both you and opponent are in kill range or close to it. Your opponent thinks you can't cast anything because your Eidolon is out and you're at 2 life. Surprise! We cast collateral and two more spells without taking any damage.
Should be how it works.