Contagion Clasp

Bracket

• B1 Exhibition — allowed: No restriction at this bracket
• B2 Core — allowed: No restriction at this bracket
• B3 Upgraded — allowed: No restriction at this bracket
• B4 Optimized — allowed: No restriction beyond the banned list
• B5 cEDH — allowed: No restriction beyond the banned list

Why

• No Game Changer, mass land denial, extra turn, tutor or two-card combo

How Lotus Vault estimates a bracket

Bracket: Lotus Vault analysis, with Commander Spellbook flags

Combos

27 known combos.

• Tekuthal, Inquiry Dominus + Magistrate's Scepter + Coretapper + Contagion Clasp
  Produces: Infinite turns, Lock
  View on Commander Spellbook
• Magosi, the Waterveil + Nesting Grounds + Contagion Clasp
  Produces: Infinite turns, Lock
  View on Commander Spellbook
• Kurkesh, Onakke Ancient + Magistrate's Scepter + Contagion Clasp
  Produces: Infinite turns, Lock
  View on Commander Spellbook

Combos: Commander Spellbook

Rulings

• 2023-02-04 · Wizards of the Coast
  An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
• 2023-02-04 · Wizards of the Coast
  To proliferate, you can choose any permanent that has a counter, including ones controlled by opponents. You can choose any player who has a counter, including opponents. You can't choose cards in any zone other than the battlefield, even if they have counters on them.
• 2023-02-04 · Wizards of the Coast
  You don't have to choose every permanent or player that has a counter, only the ones you want to add another counter to. Since "any number" includes zero, you don't have to choose any permanents at all, and you don't have to choose any players at all.
• 2023-02-04 · Wizards of the Coast
  If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.
• 2023-02-04 · Wizards of the Coast
  Players can respond to a spell or ability whose effect includes proliferating. Once that spell or ability starts to resolve, however, and its controller chooses which permanents and players will get new counters, it's too late for anyone to respond.
• 2023-02-04 · Wizards of the Coast
  If a permanent ever has both +1/+1 counters and -1/-1 counters on it at the same time, they're removed in pairs as a state-based action so that the permanent has only one of those kinds of counters on it.
• 2011-01-01 · Wizards of the Coast
  Contagion Clasp's first ability is mandatory. If you're the only player who controls a creature, you must target one of them.

Rulings: Scryfall · Wizards of the Coast