Opus

Keywords · intermediate

Opus is an ability word. It has no rules meaning of its own (CR 207.2c) — every opus ability triggers when you cast an instant or sorcery spell, then checks how much mana you spent on it.

How it works

• Opus abilities all read "Whenever you cast an instant or sorcery spell, [base effect]." Every one of them also checks whether five or more mana was spent on that spell.
• Effects include temporary power/toughness pumps, milling cards, a draw-then-discard, gaining double strike, and putting +1/+1 counters on the opus creature.
• What the five-mana check changes differs by card: it can replace the base effect with a bigger one, remove a downside (like skipping the discard), or add something extra on top of the base effect.

Rules notes

• "Five or more mana was spent" checks the mana actually paid for that spell, not just its printed mana cost.
• The base part of each opus ability always happens on a qualifying cast — the five-mana check only affects the size or nature of the payoff.
• The trigger is set off by casting, so it fires even if the spell is later countered.

Rule reference

[207.2c]