For each

From Archon Arcana

Some abilities include an effect that uses the term “for each” to determine the magnitude of the effect. Unless otherwise specified, a player may choose to affect a different card with each instance of such an effect.

Example: Shard of Pain reads “Play: Deal 1 damage to an enemy creature for each friendly Shard.” That damage may be distributed among multiple creatures.

Some abilities specify that a player must “choose a creature,” then do an effect to that creature using the term “for each.” Such abilities only affect a single creature.

Example: Red Planet Ray Gun reads “This creature gains, “Reap: Choose a creature. Deal 1 damage to that creature for each Mars creature in play.”” That damage must be dealt only to the chosen creature—it cannot be distributed among multiple creatures.

Official rules v1.7 December 2020