Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Fyndhorn Elves

Elvish Mystic

Voice of the Woods

Tap five untapped Elves you control: Create a 7/7 green Elemental creature token with trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Arbor Elf

Llanowar Elves

Quirion Ranger

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Defiant Elf

Taunting Elf

All creatures able to block Taunting Elf do so.

Wirewood Elf

Prime Speaker Vannifar

{T}, Sacrifice another creature: Search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put that card onto the battlefield, then shuffle. Activate only as a sorcery.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.