None keeps a deck in Bracket 1 or 2. One to three make it Bracket 3, and four or more make it Bracket 4.

A combo raises the deck to its own bracket. A fast two-card infinite is Bracket 4.

• Maskwood Nexus + The World Tree Bracket 2
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  • 
  • Put all creature cards from your library onto the battlefield
  Steps on Commander Spellbook
• Biovisionary + Rite of Replication Bracket 2
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  • 
  • Win the game
  Steps on Commander Spellbook

Any rules out Bracket 1. Brackets 2 and 3 allow a few, never chained or looped; Icarian counts three or more as Bracket 3.

Any at all makes it Bracket 4. Brackets 1 to 3 don't allow it.