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}.)

Go for Blood

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
Cycling {1} ({1}, Discard this card: Draw a card.)

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.

Joust

Choose target creature you control and target creature you don't control. The creature you control gets +2/+1 until end of turn if it's a Knight. Then those creatures fight each other. (Each deals damage equal to its power to the other.)

Arni Slays the Troll

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Target creature you control fights up to one target creature you don't control.
II — Add {R}. Put two +1/+1 counters on up to one target creature you control.
III — You gain life equal to the greatest power among creatures you control.

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.

Savage Punch

Target creature you control fights target creature you don't control.
Ferocious — The creature you control gets +2/+2 until end of turn before it fights if you control a creature with power 4 or greater.

Wicked Wolf

When Wicked Wolf enters, it fights up to one target creature you don't control.
Sacrifice a Food: Put a +1/+1 counter on Wicked Wolf. It gains indestructible until end of turn. Tap it.

Struggle for Skemfar

Put a +1/+1 counter on target creature you control. Then that creature fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)
Foretell {G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Pounce

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

Bushwhack

Choose one —
• Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
• Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Pheres-Band Brawler

When Pheres-Band Brawler enters, it fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)

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.

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."

Arena

{3}, {T}: Tap target creature you control and target creature of an opponent's choice they control. Those creatures fight each other. (Each deals damage equal to its power to the other.)

Gruul Ragebeast

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

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."

Somberwald Stag

When Somberwald Stag enters, you may have it fight target creature you don't control.

Ravager Wurm

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
When Ravager Wurm enters, choose up to one —
• Ravager Wurm fights target creature you don't control.
• Destroy target land with an activated ability that isn't a mana ability.

Guild Feud

At the beginning of your upkeep, target opponent reveals the top three cards of their library, may put a creature card from among them onto the battlefield, then puts the rest into their graveyard. You do the same with the top three cards of your library. If two creatures are put onto the battlefield this way, those creatures fight each other.

Pit Fight

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

Markov Enforcer

Whenever Markov Enforcer or another Vampire you control enters, Markov Enforcer fights up to one target creature an opponent controls.
Whenever a creature dealt damage by Markov Enforcer this turn dies, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Tovolar's Packleader

Whenever Tovolar's Packleader enters or attacks, create two 2/2 green Wolf creature tokens.
{2}{G}{G}: Another target Wolf or Werewolf you control fights target creature you don't control.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Tovolar's Huntmaster

When Tovolar's Huntmaster enters, create two 2/2 green Wolf creature tokens.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Tovolar's Huntmaster // Tovolar's Packleader

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.

Thorn Mammoth

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

Affectionate Indrik

When this creature enters, you may have it fight target creature you don't control. (Each deals damage equal to its power to the other.)

Contested Cliffs

{T}: Add {C}.
{R}{G}, {T}: Target Beast creature you control fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

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. (Each deals damage equal to its power to the other.)

Cartouche of Strength

Enchant creature you control
When Cartouche of Strength enters, you may have enchanted creature fight target creature an opponent controls. (Each deals damage equal to its power to the other.)
Enchanted creature gets +1/+1 and has trample.

Gold-Forge Garrison

(Transforms from Golden Guardian.)
{T}: Add two mana of any one color.
{4}, {T}: Create a 4/4 colorless Golem artifact creature token.

Golden Guardian

Defender
{2}: Golden Guardian fights another target creature you control. When Golden Guardian dies this turn, return it to the battlefield transformed under your control.

Golden Guardian // Gold-Forge Garrison

Nightfall Predator

{R}, {T}: Nightfall Predator fights target creature. (Each deals damage equal to its power to the other.)
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Nightfall Predator.

Daybreak Ranger

{T}: Daybreak Ranger deals 2 damage to target creature with flying.
At the beginning of each upkeep, if no spells were cast last turn, transform Daybreak Ranger.