Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Elvish Mystic

Soul Warden

Whenever another creature enters, you gain 1 life.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Trelasarra, Moon Dancer

Whenever you gain life, put a +1/+1 counter on Trelasarra, Moon Dancer and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Wellwisher

{T}: You gain 1 life for each Elf on the battlefield.

Priest of Titania

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

Jetmir, Nexus of Revels

Creatures you control get +1/+0 and have vigilance as long as you control three or more creatures.
Creatures you control also get +1/+0 and have trample as long as you control six or more creatures.
Creatures you control also get +1/+0 and have double strike as long as you control nine or more creatures.