Mana Leak

Counter target spell unless its controller pays {3}.

Snake Umbra

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals damage to an opponent, you may draw a card."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Season of Growth

Whenever a creature you control enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Whenever you cast a spell that targets a creature you control, draw a card.

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When this Aura is put into a graveyard from the battlefield, return it to its owner's hand.

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Invisible Stalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
This creature can't be blocked.

Misty Rainforest

{T}, Pay 1 life, Sacrifice this land: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Island

Gladecover Scout

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Hedge Maze

({T}: Add {G} or {U}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Nature's Claim

Destroy target artifact or enchantment. Its controller gains 4 life.

Voidslime

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Slippery Bogle

Forest

Cartouche of Knowledge

Enchant creature you control
When this Aura enters, draw a card.
Enchanted creature gets +1/+1 and has flying.

Counterspell

Favor of the Overbeing

Enchant creature
As long as enchanted creature is green, it gets +1/+1 and has vigilance.
As long as enchanted creature is blue, it gets +1/+1 and has flying.

Rune of Might

Enchant permanent
When this Aura enters, draw a card.
As long as enchanted permanent is a creature, it gets +1/+1 and has trample.
As long as enchanted permanent is an Equipment, it has "Equipped creature gets +1/+1 and has trample."