For bosses, if it's one of the vanilla bosses or a custom boss that uses A_BossDeath in its death states, 2.1 now reserves tags -4 and -3 for boss death linedef executor effects. -4 is used whenever a single boss dies, and -3 is used whenever all bosses in the map have died.
There's nothing like that for enemies on the other hand, so yes A_LinedefExecute is your best option then.