Ulvenwald Tracker

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

Engulfing Slagwurm

Whenever this creature blocks or becomes blocked by a creature, destroy that creature. You gain life equal to that creature's toughness.

Foe-Razer Regent

Flying
When this creature enters, you may have it fight target creature you don't control.
Whenever a creature you control fights, put two +1/+1 counters on it at the beginning of the next end step.

Elven Warhounds

Whenever this creature becomes blocked by a creature, put that creature on top of its owner's library.

Nacatl War-Pride

This creature must be blocked by exactly one creature if able.
Whenever this creature attacks, create X tokens that are copies of it and that are tapped and attacking, where X is the number of creatures defending player controls. Exile the tokens at the beginning of the next end step.

Nessian Boar

All creatures able to block this creature do so.
Whenever this creature becomes blocked by a creature, that creature's controller draws a card.

No Quarter

Whenever a creature becomes blocked by a creature with lesser power, destroy the blocking creature.
Whenever a creature blocks a creature with lesser power, destroy the attacking creature.

Lure

Enchant creature
All creatures able to block enchanted creature do so.

Rock Basilisk

Whenever this creature blocks or becomes blocked by a non-Wall creature, destroy that creature at end of combat.

Thresher Beast

Whenever this creature becomes blocked, defending player sacrifices a land of their choice.

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Sylvan Basilisk

Whenever this creature becomes blocked by a creature, destroy that creature.

Deepwood Tantiv

Whenever this creature becomes blocked, you gain 2 life.

Thorn Mammoth

Trample
Whenever this creature or another creature you control enters, this creature fights up to one target creature you don't control.

Gruul Ragebeast

Whenever this creature or another creature you control enters, that creature fights target creature an opponent controls.

Grothama, All-Devouring

Other creatures have "Whenever this creature attacks, you may have it fight Grothama, All-Devouring."
When Grothama leaves the battlefield, each player draws cards equal to the amount of damage dealt to Grothama this turn by sources they controlled.

Apex Altisaur

When this creature enters, it fights up to one target creature you don't control.
Enrage — Whenever this creature is dealt damage, it fights up to one target creature you don't control.