Bloaks are just sproutlings controlling wood, so it that's wheres spoutlings summon from, also 2 of the plant mechs spawn on the final wave along with sprout himself, in his giant wood constructed from wood, also all enemies besides pyrotechnetic and other metal type enemies (discluding sprout) take more damage from fire type towers.
ALSO I KNOW THAT ITS JUST A REGULAR PLANT IN THE SPROUT MECH, THATS AN ERROR IM TO LAZY TO FIX no affiliated with dandy's world.