Cast this spell only during combat before blockers are declared.
Untap target attacking creature and remove it from combat. Gain control of that creature until end of turn.
If a turn has multiple combat phases, this spell can be cast during any of them as long as it’s before the beginning of that phase’s Declare Blockers Step.
If you cast Disharmony during an opponent’s turn, you may then block with the creature you gain control of (assuming there’s an attacking creature it can block).
Disharmony can target a creature you control.
The current wording explicitly removes the creature from combat. It is no longer an attacking or blocking creature.
Disharmony works even if the attacker was not tapped to attack.
The creature untaps (if it was tapped) before you get control of it.