Gargos, Vicious Watcher

Vigilance
Hydra spells you cast cost {4} less to cast.
Whenever a creature you control becomes the target of a spell, Gargos, Vicious Watcher fights up to one target creature you don't control.

Hankyu

Equipped creature has "{T}: Put an aim counter on Hankyu" and "{T}, Remove all aim counters from Hankyu: This creature deals damage to any target equal to the number of aim counters removed this way."
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)

Vivien of the Arkbow

+2: Put two +1/+1 counters on up to one target creature.
−3: Target creature you control deals damage equal to its power to target creature you don't control.
−9: Creatures you control get +4/+4 and gain trample until end of turn.

Gargantuan Gorilla

At the beginning of your upkeep, you may sacrifice a Forest. If you sacrifice a snow Forest this way, Gargantuan Gorilla gains trample until end of turn. If you don't sacrifice a Forest, sacrifice Gargantuan Gorilla and it deals 7 damage to you.
{T}: Gargantuan Gorilla deals damage equal to its power to another target creature. That creature deals damage equal to its power to Gargantuan Gorilla.

Elvish Bard

All creatures able to block Elvish Bard do so.

Savage Stomp

This spell costs {2} less to cast if it targets a Dinosaur you control.
Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)

Shinen of Life's Roar

All creatures able to block Shinen of Life's Roar do so.
Channel — {2}{G}{G}, Discard Shinen of Life's Roar: All creatures able to block target creature this turn do so.

Tempting Licid

{G}, {T}: Tempting Licid loses this ability and becomes an Aura enchantment with enchant creature. Attach it to target creature. You may pay {G} to end this effect.
All creatures able to block enchanted creature do so.

Lure

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

Titanic Brawl

This spell costs {1} less to cast if it targets a creature you control with a +1/+1 counter on it.
Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Declare Dominance

Target creature gets +3/+3 until end of turn. All creatures able to block it this turn do so.

Prey Upon

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

Revenge of the Hunted

Until end of turn, target creature gets +6/+6 and gains trample, and all creatures able to block it this turn do so.
Miracle {G} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Noble Quarry

Bestow {5}{G} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
All creatures able to block Noble Quarry or enchanted creature do so.
Enchanted creature gets +1/+1.

Time to Feed

Choose target creature an opponent controls. When that creature dies this turn, you gain 3 life. Target creature you control fights that creature. (Each deals damage equal to its power to the other.)

Vivien, Arkbow Ranger

+1: Distribute two +1/+1 counters among up to two target creatures. They gain trample until end of turn.
−3: Target creature you control deals damage equal to its power to target creature or planeswalker.
−5: You may reveal a creature card you own from outside the game and put it into your hand.

Ulvenwald Tracker

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

Aggressive Instinct

Target creature you control deals damage equal to its power to target creature you don't control.

Nemesis Mask

All creatures able to block equipped creature do so.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the creature leaves.)

Unnatural Aggression

Devoid (This card has no color.)
Target creature you control fights target creature an opponent controls. If the creature an opponent controls would die this turn, exile it instead.

Apex Altisaur

When Apex Altisaur enters the battlefield, 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.

Ancient Animus

Put a +1/+1 counter on target creature you control if it's legendary. Then it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Savage Swipe

Target creature you control gets +2/+2 until end of turn if its power is 2. Then it fights target creature you don't control. (Each deals damage equal to its power to the other.)

Breaker of Armies

All creatures able to block Breaker of Armies do so.

Outmuscle

Put a +1/+1 counter on target creature you control, then it fights target creature you don't control. (Each deals damage equal to its power to the other.)
Adamant — If at least three green mana was spent to cast this spell, the creature you control gains indestructible until end of turn.

Treeshaker Chimera

All creatures able to block Treeshaker Chimera do so.
When Treeshaker Chimera dies, draw three cards.

Roar of Challenge

All creatures able to block target creature this turn do so.
Ferocious — That creature gains indestructible until end of turn if you control a creature with power 4 or greater.

God-Eternal Rhonas

Deathtouch
When God-Eternal Rhonas enters the battlefield, double the power of each other creature you control until end of turn. Those creatures gain vigilance until end of turn.
When God-Eternal Rhonas dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Nessian Boar

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

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.

Bloodscent

All creatures able to block target creature this turn do so.

Ambuscade

Target creature you control gets +1/+0 until end of turn. It deals damage equal to its power to target creature an opponent controls.

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.

Taunting Challenge

Hunt the Weak

Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)

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."

Nissa's Judgment

Support 2. (Put a +1/+1 counter on each of up to two target creatures.)
Choose up to one target creature an opponent controls. Each creature you control with a +1/+1 counter on it deals damage equal to its power to that creature.

Clear Shot

Target creature you control gets +1/+1 until end of turn. It deals damage equal to its power to target creature you don't control.

Predatory Urge

Enchant creature
Enchanted creature has "{T}: This creature deals damage equal to its power to target creature. That creature deals damage equal to its power to this creature."

Thorn Mammoth

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

Triangle of War

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

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.)

Rabid Bite

Nath's Elite

All creatures able to block Nath's Elite do so.
When Nath's Elite enters the battlefield, clash with an opponent. If you win, put a +1/+1 counter on Nath's Elite. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Golgari Decoy

All creatures able to block Golgari Decoy do so.
Scavenge {3}{G}{G} ({3}{G}{G}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Wing Puncture

Target creature you control deals damage equal to its power to target creature with flying.

Cartouche of Strength

Enchant creature you control
When Cartouche of Strength enters the battlefield, 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.

Nature's Way

Target creature you control gains vigilance and trample until end of turn. It deals damage equal to its power to target creature you don't control.

Rhonas the Indomitable

Deathtouch, indestructible
Rhonas the Indomitable can't attack or block unless you control another creature with power 4 or greater.
{2}{G}: Another target creature gets +2/+0 and gains trample until end of turn.

Warbriar Blessing

Enchant creature you control
When Warbriar Blessing enters the battlefield, enchanted creature fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)
Enchanted creature gets +0/+2.

Prized Unicorn

All creatures able to block Prized Unicorn do so.

Wild Instincts

Target creature you control gets +2/+2 until end of turn. It fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Hunt the Hunter

Target green creature you control gets +2/+2 until end of turn. It fights target green creature an opponent controls.

Surestrike Trident

Equipped creature has first strike and "{T}, Unattach Surestrike Trident: This creature deals damage equal to its power to target player or planeswalker."
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the creature leaves.)

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.

Pounce

Taunting Elf

All creatures able to block Taunting Elf do so.

Seton's Desire

Enchant creature
Enchanted creature gets +2/+2.
Threshold — As long as seven or more cards are in your graveyard, all creatures able to block enchanted creature do so.

Epic Confrontation

Target creature you control gets +1/+2 until end of turn. It fights target creature you don't control. (Each deals damage equal to its power to the other.)