Pounce

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Traverse the Outlands

Search your library for up to X basic land cards, where X is the greatest power among creatures you control. Put those cards onto the battlefield tapped, then shuffle.

Ulvenwald Tracker

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

Domri Rade

+1: Look at the top card of your library. If it's a creature card, you may reveal it and put it into your hand.
−2: Target creature you control fights another target creature.
−7: You get an emblem with "Creatures you control have double strike, trample, hexproof, and haste."

Primeval Protector

This spell costs {1} less to cast for each creature your opponents control.
When Primeval Protector enters, put a +1/+1 counter on each other creature you control.

Ezuri's Predation

For each creature your opponents control, create a 4/4 green Phyrexian Beast creature token. Each of those tokens fights a different one of those creatures.

Foe-Razer Regent

Flying
When Foe-Razer Regent 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.

Setessan Tactics

Strive — This spell costs {G} more to cast for each target beyond the first.
Until end of turn, any number of target creatures each get +1/+1 and gain "{T}: This creature fights another target creature."

Gruul Ragebeast

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

Elvish Mystic

Pit Fight

Target creature you control fights another target creature. (Each deals damage equal to its power to the other.)

Apex Altisaur

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

Ohran Frostfang

Attacking creatures you control have deathtouch.
Whenever a creature you control deals combat damage to a player, draw a card.

Thorn Mammoth

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

Dolmen Gate

Prevent all combat damage that would be dealt to attacking creatures you control.

Vigor

Trample
If damage would be dealt to another creature you control, prevent that damage. Put a +1/+1 counter on that creature for each 1 damage prevented this way.
When Vigor is put into a graveyard from anywhere, shuffle it into its owner's library.

Rampant Growth

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

Prey Upon

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Llanowar Elves

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Birds of Paradise

Ripjaw Raptor

Enrage — Whenever Ripjaw Raptor is dealt damage, draw a card.

Domri, Anarch of Bolas

Creatures you control get +1/+0.
+1: Add {R} or {G}. Creature spells you cast this turn can't be countered.
−2: Target creature you control fights target creature you don't control.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Sol Ring

Kogla, the Titan Ape

When Kogla, the Titan Ape enters, it fights up to one target creature you don't control.
Whenever Kogla attacks, destroy target artifact or enchantment defending player controls.
{1}{G}: Return target Human you control to its owner's hand. Kogla gains indestructible until end of turn.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Primal Might

Target creature you control gets +X/+X until end of turn. Then it fights up to one target creature you don't control.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Neyith of the Dire Hunt

Whenever one or more creatures you control fight or become blocked, draw a card.
At the beginning of combat on your turn, you may pay {2}{R/G}. If you do, double target creature's power until end of turn. That creature must be blocked this combat if able. ({R/G} can be paid with either {R} or {G}.)