Two important things to remember about triggers: Abilities may trigger during the resolution of a spell or ability, but are not put on the stack until after state based actions (SBAs) are checked. A triggered ability is a game object independent of the source that created it.
As the first Guild Feud resolves, Mwonvuli Beast Tracker and Acidic Slime are placed on the battlefield. Each creature has an enters-the-battlefield (ETB) ability that triggers immediately, but is not put on the stack until after SBAs, before any player receives priority. The two creatures fight and both creatures die. The triggers are placed on the stack in Active Player, Non-Active Player (APNAP) order. Nicky is the NAP, since it is Ashley’s turn. Because abilities are independent game objects, it does not matter that the creatures died, as their triggered abilities will still resolve normally. After Acidic Slime’s ability resolves, Ashley searches for a creature with deathtouch, hexproof, reach or trample to put on top of her library after shuffling. Ashley finds Vampire Nighthawk.
As the second Guild Feud ability resolves, Nicky reveals Angel of Serenity and Ashley reveals the Vampire Nighthawk, which are both placed on the battlefield. Angel of Serenity‘s ETB ability triggers, but is not put on the stack yet. Angel of Serenity is destroyed by the deathtouch damage from Nighthawk, so its leaves-the-battlefield (LTB) ability also triggers. Before any player receives priority, the triggers are placed on the stack in APNAP order. All the triggers are controlled by Nicky, so Nicky chooses the order in which they are placed on the stack.
If Nicky chooses to put the ETB trigger on the stack first then the LTB trigger above it, the LTB resolves first. Since nothing has been exiled yet, it resolves and returns nothing. Then the ETB trigger exiles the chosen targets permanently, without a linked ability to bring them back. If Nicky chooses to put the ETB trigger on the stack second, it will resolve first. Up to three targets can be exiled. The Angel of Serenity can be chosen as a target, because it was put in the graveyard before the triggered ability was put on the stack. Since the Angel that created the trigger is in the graveyard, it no longer recognizes itself as the source of the trigger, so it can be targeted in the graveyard. Then the LTB trigger resolves, putting the exiled cards back in their owners’ hands.
One last point to cover, as suggested by a reader: Guild Feud can’t put any creatures onto the battlefield while there’s a Grafdigger’s Cage around. Since the cards you look at are still part of the library, you can reveal a creature card, but it won’t be able to enter the battlefield, and will just end up in the graveyard instead.
Today’s Rules Tip written by Jacob Faturechi, L2 from Los Angeles, CA