Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Oko, Thief of Crowns

+2: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
+1: Target artifact or creature loses all abilities and becomes a green Elk creature with base power and toughness 3/3.
−5: Exchange control of target artifact or creature you control and target creature an opponent controls with power 3 or less.

Befuddle

Target creature gets -4/-0 until end of turn.
Draw a card.

Rings of Brighthearth

Whenever you activate an ability, if it isn't a mana ability, you may pay {2}. If you do, copy that ability. You may choose new targets for the copy.

Mana Leak

Counter target spell unless its controller pays {3}.

Forest

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Tidechannel Pathway

Barkchannel Pathway

Barkchannel Pathway // Tidechannel Pathway

Serum Visions

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Island

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.