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Off the top of my head:
Defense of the heart - costs 4, requires the opponent to have 3 or more creatures, is an enchantment, gets you two creatures though
Tooth and Nail - costs a shitload, but gets 2 creatures, no questions asked.
Elvish Piper - costs 4, is a creature, can be activated for G and tap to put something from your hand into play.
Natural Order - costs 4, sorcery, gets a green creature, requires you to sacrifice a green creature.
Entomb/Buried Alive + Reanimate, Animate Dead, Zombify, Makeshift Mannequin, any other reanimate spell.