Twinning Staff

Bracket

• B1 Exhibition — Not in the same deck as its two-card combo partners: Narset's Reversal, Dramatic Reversal, Fury Storm
• B2 Core — Not in the same deck as its two-card combo partners: Narset's Reversal, Dramatic Reversal, Fury Storm
• B3 Upgraded — Not in the same deck as its early two-card combo partner: Fury Storm
• B4 Optimized — allowed: No restriction beyond the banned list
• B5 cEDH — allowed: No restriction beyond the banned list

Why

• Two-card combo with Narset's Reversal, Dramatic Reversal, Fury Storm (early with Fury Storm)

How Lotus Vault estimates a bracket

Bracket: Lotus Vault analysis, with Commander Spellbook flags

Combos

56 known combos, 3 of them two-card.

• Twinning Staff + Narset's Reversal
  Produces: Infinite magecraft triggers
  View on Commander Spellbook
• Twinning Staff + Dramatic Reversal
  Produces: Infinite magecraft triggers, Infinite mana nonland permanents you control can produce
  View on Commander Spellbook
• Fury Storm + Twinning Staff
  Produces: Infinite copies of instant and sorcery spells on the stack, Infinite magecraft triggers
  View on Commander Spellbook

Combos: Commander Spellbook

Rulings

• 2020-04-17 · Wizards of the Coast
  You may choose new targets for the additional copy, even if you can't choose new targets for the original copy or copies.
• 2020-04-17 · Wizards of the Coast
  You choose whether the additional copy is put onto the stack before or after the original copy. If a spell is being copied more than once, you can even have the additional copy put onto the stack in between the original copies.
• 2020-04-17 · Wizards of the Coast
  Twinning Staff's last ability can copy any instant or sorcery spell you control, not just one with targets.
• 2020-04-17 · Wizards of the Coast
  The copy is created on the stack, so it's not “cast.” Abilities that trigger when a player casts a spell won't trigger. It will resolve before the original spell does.
• 2020-04-17 · Wizards of the Coast
  If you have a second Twinning Staff, copying a spell results in two additional copies. If you have a third, you get three additional copies, and so on.
• 2020-04-17 · Wizards of the Coast
  If the spell that's copied is modal (that is, it says “Choose one —” or the like), the copy will have the same mode. A different mode can't be chosen.
• 2020-04-17 · Wizards of the Coast
  The copy will have the same targets as the spell it's copying unless you choose new ones. You may change any number of the targets, including all of them or none of them. If, for one of the targets, you can't choose a new legal target, then it remains unchanged (even if the current target is illegal).
• 2020-04-17 · Wizards of the Coast
  If an effect copies a card rather than a spell (such as that of God-Eternal Kefnet), this doesn't cause an additional copy to be created.
• 2020-04-17 · Wizards of the Coast
  If the spell that's copied has an X whose value was determined as it was cast, the copy will have the same value of X.
• 2020-04-17 · Wizards of the Coast
  The controller of a copy can't choose to pay any alternative or additional costs for the copy. However, effects based on any alternative or additional costs that were paid for the original spell are copied as though those same costs were paid for the copy.
• 2020-04-17 · Wizards of the Coast
  If the spell has damage divided as it was cast (like Mythos of Vadrok), the division can't be changed, although the targets receiving that damage still can. The same is true of spells that distribute counters.

Rulings: Scryfall · Wizards of the Coast