Swamp

Bone Picker

This spell costs {3} less to cast if a creature died this turn.
Flying, deathtouch

Writhing Necromass

This spell costs {1} less to cast for each creature card in your graveyard.
Deathtouch

Rubblebelt Maverick

When Rubblebelt Maverick enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{G}, Exile Rubblebelt Maverick from your graveyard: Put a +1/+1 counter on target creature. Activate only as a sorcery.

Forest

Bayou Groff

As an additional cost to cast this spell, sacrifice a creature or pay {3}.

Altar's Reap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Fanatical Offering

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Young Wolf

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Tocasia's Dig Site

{T}: Add {C}.
{3}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Llanowar Elves

Blood Pet

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.