Idea from Taranis01

something like this?

drop: CREATURE_SPIDER
aggression: NEUTRAL (or AGGRESSIVE, FRIENDLY)

Probably not possible as stated... at least, not for mobs other than wolves and pig zombies. Unless you worked together with Friendly (once I get around to expanding it).

Yeah, would be nice to work it in with Friendly perhaps an API to tell Friendly to set the agression after dropping the entity?