Activate Brazen Freebooter by paying {1}{U}, blinking it.
When Brazen Freebooter enters, it and Deadeye Navigator's soulbond ability trigger
Resolve the Deadeye Navigator trigger, repairing it and Brazen Freebooter.
Resolve the Brazen Freebooter trigger, creating two Treasure tokens.
Activate both Treasures by tapping and sacrificing them, adding {1}{U}.
Repeat.

Infinite LTB

Infinite ETB

Deadeye Navigator

Xorn

Brazen Freebooter

Activate Ashnod's Altar by sacrificing Brazen Freebooter, adding {C}{C}.
Brazen Freebooter dies, triggering Nim Deathmantle, causing you to pay {4} to return Brazen Freebooter from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Brazen Freebooter enters the battlefield, creating two Treasure tokens.
Activate two Treasure tokens by tapping and sacrificing those, adding two mana of any color.
Repeat.

Infinite death triggers

Infinite sacrifice triggers

Nim Deathmantle

Ashnod's Altar

Activate Brazen Freebooter by paying {1}{U}, blinking it.
When Brazen Freebooter enters, it and Deadeye Navigator's soulbond ability trigger twice.
Resolve both Deadeye Navigator triggers, repairing it and Brazen Freebooter.
Resolve both Brazen Freebooter triggers, creating two Treasure tokens.
Activate both Treasures by tapping and sacrificing them, adding {1}{U}.
Repeat.

Panharmonicon

Activate Emiel the Blessed by paying {1}, blinking Brazen Freebooter.
When Brazen Freebooter enters the battlefield, it triggers, creating a Treasure artifact token.
Activate the Treasure by tapping and sacrificing it, adding {1}.
Repeat.

Emiel the Blessed

Zirda, the Dawnwaker

Activate Ashnod's Altar by sacrificing Brazen Freebooter, adding {C}{C}.
When Brazen Freebooter dies, Mazzy's second ability and Gift of Immortality trigger.
Resolve the Mazzy trigger, exiling Gift of Immortality with the ability to cast it until end of your next turn.
Resolve the Gift of Immortality trigger, returning Brazen Freebooter from your graveyard to the battlefield.
When Brazen Freebooter enters, it triggers, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding {W}.
Cast Gift of Immortality from exile by paying {2}{W}, attaching it to Brazen Freebooter.
Repeat.

Infinite storm count

Mazzy, Truesword Paladin

Gift of Immortality

Activate Emiel the Blessed by paying {3}, blinking Brazen Freebooter.
When Brazen Freebooter enters the battlefield, it triggers once, and Preston triggers twice.
Resolve the Brazen Freebooter trigger, creating a Treasure token.
Resolve the first Preston trigger, creating a token copy of Brazen Freebooter that is a 0/1 Illusion.
When the Brazen Freebooter token enters the battlefield, it triggers, creating a Treasure token.
Repeat from step 4 for the remaining Preston trigger.
Activate three Treasures by tapping and sacrificing them, adding {3}.
Repeat.

Combos with "Brazen Freebooter"