the first time you cast the other. A player loses the game after having been dealt 21 combat damage from any one of them, not from both of them combined (although your Background won’t usually be a creature anyway).Karlach, Fury of Avernus gives red combat decks an additional attack when they attack during the first combat phase of the turn. Her trigger untaps attacking creatures, gives them first strike until end of turn, and adds another combat phase. Karlach does not need to attack herself, allowing existing creatures to benefit even on the turn she enters without haste.
Equipment carriers and creatures with attack triggers appreciate the extra combat. Sword of the Animist can search again when its equipped creature attacks a second time, while Dragons and other substantial attackers get another opportunity to connect. First strike can help the initial attackers survive blocks, improving their chances of remaining useful for the added combat.
The trigger untaps attacking creatures specifically, not every creature you control. Mana creatures left behind and other tapped nonattackers do not automatically become available. The additional phase is a combat phase without an added main phase, so you cannot assume a normal sorcery-speed window between the two attacks.
As a commander, Karlach can be paired with an eligible Background through choose a Background, letting the supporting enchantment shape the deck's colors and combat plan. In the main deck, she is a straightforward payoff for an established attacking board. Deploy her before combat when the existing attackers can use the bonus, and plan around the fact that her trigger applies only during the first combat phase of the turn.
