Jeska, Thrice Reborn

Jeska, Thrice Reborn enters with a loyalty counter on her for each time you've cast a commander from the command zone this game.
0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.
−X: Jeska, Thrice Reborn deals X damage to each of up to three targets.
Jeska, Thrice Reborn can be your commander.
Partner

Wrecking Ogre

Double strike
Bloodrush — {3}{R}{R}, Discard Wrecking Ogre: Target attacking creature gets +3/+3 and gains double strike until end of turn.

Scorchwalker

Bloodrush — {1}{R}{R}, Discard Scorchwalker: Target attacking creature gets +5/+1 until end of turn.

Mother of Runes

{T}: Target creature you control gains protection from the color of your choice until end of turn.

Luminarch Aspirant

At the beginning of combat on your turn, put a +1/+1 counter on target creature you control.

Acorn Catapult

{1}, {T}: Acorn Catapult deals 1 damage to any target. That permanent's controller or that player creates a 1/1 green Squirrel creature token.

Bruse Tarl, Boorish Herder

Whenever Bruse Tarl, Boorish Herder enters or attacks, target creature you control gains double strike and lifelink until end of turn.
Partner (You can have two commanders if both have partner.)

Oblivion Stone

{4}, {T}: Put a fate counter on target permanent.
{5}, {T}, Sacrifice Oblivion Stone: Destroy each nonland permanent without a fate counter on it, then remove all fate counters from all permanents.

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.

Rubblebelt Maaka

Bloodrush — {R}, Discard Rubblebelt Maaka: Target attacking creature gets +3/+3 until end of turn.

Agrus Kos, Eternal Soldier

Vigilance
Whenever Agrus Kos, Eternal Soldier becomes the target of an ability that targets only it, you may pay {1}{R/W}. If you do, copy that ability for each other creature you control that ability could target. Each copy targets a different one of those creatures. ({R/W} can be paid with either {R} or {W}.)

Pyrewild Shaman

Bloodrush — {1}{R}, Discard Pyrewild Shaman: Target attacking creature gets +3/+1 until end of turn.
Whenever one or more creatures you control deal combat damage to a player, if Pyrewild Shaman is in your graveyard, you may pay {3}. If you do, return Pyrewild Shaman to your hand.

Duelist's Heritage

Whenever one or more creatures attack, you may have target attacking creature gain double strike until end of turn.

Duke Ulder Ravengard

At the beginning of combat on your turn, another target creature you control gains haste and myriad until end of turn. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Ajani, Caller of the Pride

+1: Put a +1/+1 counter on up to one target creature.
−3: Target creature gains flying and double strike until end of turn.
−8: Create X 2/2 white Cat creature tokens, where X is your life total.

Gideon, Battle-Forged

+2: Up to one target creature an opponent controls attacks Gideon, Battle-Forged during its controller's next turn if able.
+1: Until your next turn, target creature gains indestructible. Untap that creature.
0: Until end of turn, Gideon, Battle-Forged becomes a 4/4 Human Soldier creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.

Kytheon, Hero of Akros

At end of combat, if Kytheon, Hero of Akros and at least two other creatures attacked this combat, exile Kytheon, then return him to the battlefield transformed under his owner's control.
{2}{W}: Kytheon gains indestructible until end of turn.