Warchief Giant

Mana cost: {3}{R}{R}
Type: Creature — Giant Warrior
Power / toughness: 5 / 3
Set: Commander 2015 #31 (uncommon)
Price: $0.88 USD

Haste
Myriad (Whenever this creature 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.)

Warchief Giant has 5 printings, first in Commander 2015 (2015). EDHREC ranks it #9,781 among Commander cards. It appears most in Gornog, the Red Reaper decks (2,527 on EDHREC). 3 public decks on TCG run it. It has 8 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: not legal
pioneer: not legal
standard: not legal
brawl: not legal

Public decks that run Warchief Giant

Seize Control - Commander 2015, led by Mizzix of the Izmagnus
Wade into Battle - Commander 2015, led by Kalemne, Disciple of Iroas
Wade into Battle - Commander Anthology Volume II, led by Kalemne, Disciple of Iroas

Commanders that run Warchief Giant most

Deck counts from EDHREC.

Often played with Warchief Giant

Cards that show up in the same decks on EDHREC.

Rulings

2015-11-04: Although the tokens enter the battlefield attacking, they were never declared as attackers. Abilities that trigger whenever a creature attacks won’t trigger, including the myriad ability of the tokens. If there any costs to have a creature attack, those costs won’t apply to the tokens.
2015-11-04: Each token copies exactly what was printed on the original creature and nothing else. It doesn’t copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.
2015-11-04: Any enters-the-battlefield abilities of the copied creature will trigger when the token enters the battlefield. Any “as [this permanent] enters the battlefield” or “[this permanent] enters the battlefield with” abilities of the copied creature will also work.
2015-11-04: If myriad creates more than one token for any given player (due to an effect such as the one Doubling Season creates), you may choose separately for each token whether it’s attacking the player or a planeswalker they control.
2015-11-04: If the defending player is your only opponent, no tokens are put onto the battlefield.
2015-11-04: The token creatures all enter the battlefield at the same time.
2015-11-04: The term “defending player” in the myriad rules (or any other ability of an attacking creature) refers to the player the creature with myriad was attacking at the time it became an attacking creature this combat, or the controller of the planeswalker the creature was attacking at the time it became an attacking creature this combat.
2015-11-04: You choose whether each token is attacking the player or a planeswalker they control as the token is created.