Swamp

Flourishing Defenses

Whenever a -1/-1 counter is put on a creature, you may create a 1/1 green Elf Warrior creature token.

Forest

Maha, Its Feathers Night

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

High Perfect Morcant

Whenever High Perfect Morcant or another Elf you control enters, each opponent blights 1. (They each put a -1/-1 counter on a creature they control.)
Tap three untapped Elves you control: Proliferate. Activate only as a sorcery. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)