Arc Runner

Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Bruse Tarl, Roving Rancher

Oxen you control have double strike.
Whenever Bruse Tarl enters or attacks, exile the top card of your library. If it's a land card, create a 2/2 white Ox creature token. Otherwise, you may cast it until the end of your next turn.

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Pillarfield Ox

Bulwark Ox

Whenever this creature attacks while saddled, put a +1/+1 counter on target creature.
Sacrifice this creature: Creatures you control with counters on them gain hexproof and indestructible until end of turn.
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Ox Drover

Vigilance
This creature can't be blocked by Oxen.
Whenever this creature enters or attacks, target opponent creates a 2/4 white Ox creature token and you draw a card.

Holy Cow

Flash
Flying
When this creature enters, you gain 2 life and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Ox of Agonas

When this creature enters, discard your hand, then draw three cards.
Escape—{R}{R}, Exile eight other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
This creature escapes with a +1/+1 counter on it.

Summon: Kujata

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Lightning — This creature deals 3 damage to each of up to two target creatures.
II — Ice — Up to three target creatures can't block this turn.
III — Fire — Discard a card, then draw two cards. When you discard a card this way, this creature deals damage equal to that card's mana value to each opponent.
Trample, haste

Earth-Origin Yak

When this creature enters, creatures you control get +1/+1 until end of turn.

Charging Cinderhorn

Haste
At the beginning of each player's end step, if no creatures attacked this turn, put a fury counter on this creature. Then this creature deals damage equal to the number of fury counters on it to that player.

Makindi Ox

Landfall — Whenever a land you control enters, tap target creature an opponent controls.

Purphoros's Emissary

Bestow {6}{R} (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.)
Menace (This creature can't be blocked except by two or more creatures.)
Enchanted creature gets +3/+3 and has menace.

Liberated Livestock

When this creature dies, create a 1/1 white Cat creature token with lifelink, a 1/1 white Bird creature token with flying, and a 2/4 white Ox creature token. For each of those tokens, you may put an Aura card from your hand and/or graveyard onto the battlefield attached to it.