Ulvenwald Tracker

{1}{G}, {T}: Target creature you control fights another target creature.

Triangle of War

{2}, Sacrifice this artifact: Target creature you control fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Fyndhorn Brownie

Satyr Piper

{3}{G}: Target creature must be blocked this turn if able.

Contagion Clasp

When this artifact enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Elder of Laurels

{3}{G}: Target creature gets +X/+X until end of turn, where X is the number of creatures you control.

Professor Hojo

The first activated ability you activate during your turn that targets a creature you control costs {2} less to activate.
Whenever one or more creatures you control become the target of an activated ability, draw a card. This ability triggers only once each turn.

Nylea, God of the Hunt

Indestructible
As long as your devotion to green is less than five, Nylea isn't a creature. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)
Other creatures you control have trample.
{3}{G}: Target creature gets +2/+2 until end of turn.

Sandstorm Verge

{T}: Add {C}.
{3}, {T}: Target creature can't block this turn. Activate only as a sorcery.

Jandor's Saddlebags

Puppet Strings

{2}, {T}: You may tap or untap target creature.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Staff of Domination

{1}: Untap this artifact.
{2}, {T}: You gain 1 life.
{3}, {T}: Untap target creature.
{4}, {T}: Tap target creature.
{5}, {T}: Draw a card.

The Skullspore Nexus

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Whenever one or more nontoken creatures you control die, create a green Fungus Dinosaur creature token with base power and toughness each equal to the total power of those creatures.
{2}, {T}: Double target creature's power until end of turn.