Dryad Arbor

(Dryad Arbor isn't a spell, it's affected by summoning sickness, and it has "{T}: Add {G}.")

Omnath, Locus of Creation

When Omnath, Locus of Creation enters, draw a card.
Landfall — Whenever a land you control enters, you gain 4 life if this is the first time this ability has resolved this turn. If it's the second time, add {R}{G}{W}{U}. If it's the third time, Omnath deals 4 damage to each opponent and each planeswalker you don't control.

Dockside Extortionist

When Dockside Extortionist enters, create X Treasure tokens, where X is the number of artifacts and enchantments your opponents control. (Treasure tokens are artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Emiel the Blessed

{3}: Exile another target creature you control, then return it to the battlefield under its owner's control.
Whenever another creature you control enters, you may pay {G/W}. If you do, put a +1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({G/W} can be paid with either {G} or {W}.)