The "Trigger" enemy: tell me about it

[_L_]

What does it do? How do I use it? (I think it's a "null" enemy designed for use with the Dungeon Boss screen flag, but it may have deeper purposes...)

[Rakki]

Well the trigger enemy WAS the way to set off Dmap and such changes (like how the town changes in A Link to Tortuga), but it's pretty much become obsolete because of Room State Carryovers in 2.11. I can't think of any uses, besides that, for it.

[C-Dawg]

What does it do? How do I use it? (I think it's a "null" enemy designed for use with the Dungeon Boss screen flag, but it may have deeper purposes...)

Essentially, yes, that was it is.

Not totally obsolete, because now you can keep track of several things at once. Room state carryovers keep track of one variable - whether or not secrets are triggered - as far as I know. Now, you can keep track of two changes at once. For instance, carryovers let you use LttP style switch block puzzles, but you could still use a trigger enemy to keep track of whether a boss within that level had been defeated. Additionally, Room state carryovers have to be linked together; trigger enemies let you make far flung changes remotely and permanently.

The way the trigger worked is it was an invisible enemy that could not be affected by Link directly. It could only be killed by picking up a "kill all enemies" item. So you'd have one room, call it A, that had a "kill all enemies" item, a trigger enemy, and the "Dungeon Boss" screen flag set. Then you have a second room (on a DMAP of the same level #!!!) with a trigger enemy also set as the "Dungeon Boss." See, once you kill the enemies in one room flagged as the Dungeon Boss, you also kill them in any other room similarly flagged. So the effect is that you killed the trigger enemy in B remotely. Now you're free to set your secret to be Enemy->Trigger in room B.

Even cooler, since we can now reset rooms, you could use the reset ability (presumably) to revitalize the trigger enemies. So you can get a toggle going on; switch in Room A kills/revives trigger enemy, killing/reviving the trigger enemies in far flung room B.