Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Giant Growth

Target creature gets +3/+3 until end of turn.

Simic Guildgate

This land enters tapped.
{T}: Add {G} or {U}.

Island

Forest

Beetleform Mage

{G}{U}: Beetleform Mage gets +2/+2 and gains flying until end of turn. Activate only once each turn.

Drakewing Krasis

Phytoburst

Target creature gets +5/+5 until end of turn.

Kraken Hatchling

Maraleaf Pixie

Titanic Growth

Target creature gets +4/+4 until end of turn.

Unsummon

Return target creature to its owner's hand.

Shambleshark

Flash (You may cast this spell any time you could cast an instant.)
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Quickling

Flash (You may cast this spell any time you could cast an instant.)
Flying
When Quickling enters, sacrifice it unless you return another creature you control to its owner's hand.