Sunshower Druid

When Sunshower Druid enters, put a +1/+1 counter on target creature and you gain 1 life.

Valley Mightcaller

Trample
Whenever another Frog, Rabbit, Raccoon, or Squirrel you control enters, put a +1/+1 counter on Valley Mightcaller.

Forest

Splash Portal

Exile target creature you control, then return it to the battlefield under its owner's control. If that creature is a Bird, Frog, Otter, or Rat, draw a card.

Mistbreath Elder

At the beginning of your upkeep, return another creature you control to its owner's hand. If you do, put a +1/+1 counter on Mistbreath Elder. Otherwise, you may return Mistbreath Elder to its owner's hand.

Dour Port-Mage

Whenever one or more other creatures you control leave the battlefield without dying, draw a card.
{1}{U}, {T}: Return another target creature you control to its owner's hand.

Pond Prophet

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Simic Guildgate

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

Polliwallop

This spell costs {1} less to cast for each Frog you control.
Target creature you control deals damage equal to twice its power to target creature you don't control.

Island

Gossip's Talent

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control enters, surveil 1.
{1}{U}: Level 2
Whenever you attack, target attacking creature with power 3 or less can't be blocked this turn.
{3}{U}: Level 3
Whenever a creature you control deals combat damage to a player, you may exile it, then return it to the battlefield under its owner's control.

Long River Lurker

Ward {1}
Other Frogs you control have ward {1}.
When Long River Lurker enters, target creature you control can't be blocked this turn. Whenever that creature deals combat damage this turn, you may exile it. If you do, return it to the battlefield under its owner's control.