No Mercy

Whenever a creature deals damage to you, destroy it.

Plaguebearer

{X}{X}{B}: Destroy target nonblack creature with mana value X.

New Frontiers

Each player may search their library for up to X basic land cards and put them onto the battlefield tapped. Then each player who searched their library this way shuffles.

Damnation

Destroy all creatures. They can't be regenerated.

Mitotic Slime

When Mitotic Slime dies, create two 2/2 green Ooze creature tokens. They have "When this creature dies, create two 1/1 green Ooze creature tokens."

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Liege of the Hollows

When Liege of the Hollows dies, each player may pay any amount of mana. Then each player creates a number of 1/1 green Squirrel creature tokens equal to the amount of mana they paid this way.

Lifeforce

Ensnaring Bridge

Creatures with power greater than the number of cards in your hand can't attack.

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

Wound Reflection

At the beginning of each end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Rite of Consumption

As an additional cost to cast this spell, sacrifice a creature.
Rite of Consumption deals damage equal to the sacrificed creature's power to target player or planeswalker. You gain life equal to the damage dealt this way.

Rath's Edge

{T}: Add {C}.
{4}, {T}, Sacrifice a land: Rath's Edge deals 1 damage to any target.

Chatter of the Squirrel

Create a 1/1 green Squirrel creature token.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mana Reflection

If you tap a permanent for mana, it produces twice as much of that mana instead.

Instill Energy

Enchant creature
Enchanted creature can attack as though it had haste.
{0}: Untap enchanted creature. Activate only during your turn and only once each turn.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.