Seize the Day

Bracket

• B1 Exhibition — Not in the same deck as its two-card combo partner: Angel of Destiny
• B2 Core — Not in the same deck as its two-card combo partner: Angel of Destiny
• B3 Upgraded — allowed: Its two-card combos are not early, which Bracket 3 allows
• B4 Optimized — allowed: No restriction beyond the banned list
• B5 cEDH — allowed: No restriction beyond the banned list

Why

• Two-card combo with Angel of Destiny (none of them early)

How Lotus Vault estimates a bracket

Bracket: Lotus Vault analysis, with Commander Spellbook flags

Combos

4 known combos, one of them two-card.

• Angel of Destiny + Seize the Day
  Produces: Each opponent loses the game
  View on Commander Spellbook
• Prossh, Skyraider of Kher + Xenagos, God of Revels + Seize the Day
  Produces: Each opponent loses the game, Near-infinite combat damage
  View on Commander Spellbook
• Sword of Feast and Famine + Sword of Hearth and Home + Ardent Elementalist + Seize the Day
  Produces: Infinite combat damage, Infinite combat phases, Infinite creature ETB
  View on Commander Spellbook

Combos: Commander Spellbook

Rulings

• 2021-03-19 · Wizards of the Coast
  You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.
• 2021-03-19 · Wizards of the Coast
  To determine the total cost of a spell, start with the mana cost or alternative cost (such as a flashback cost) you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
• 2021-03-19 · Wizards of the Coast
  If a card with flashback is put into your graveyard during your turn, you can cast it if it's legal to do so before any other player can take any actions.
• 2021-03-19 · Wizards of the Coast
  A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way.
• 2021-03-19 · Wizards of the Coast
  You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.
• 2021-03-19 · Wizards of the Coast
  "Flashback [cost]" means "You may cast this card from your graveyard by paying [cost] rather than paying its mana cost" and "If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack."
• 2018-12-07 · Wizards of the Coast
  If you somehow cast Seize the Day during an opponent's main phase, that opponent attacks during the resulting combat phase, since it's still that player's turn. If you somehow cast it not during a main phase at all, all that happens is you untap the target creature.
• 2018-12-07 · Wizards of the Coast
  Seize the Day can target a creature that's already untapped.
• 2018-12-07 · Wizards of the Coast
  If the target creature becomes an illegal target for Seize the Day, the spell doesn't resolve. There isn't an additional combat phase or main phase.

Rulings: Scryfall · Wizards of the Coast