Mazzy, Truesword Paladin | Ashnod's Altar | Gift of Immortality (and one other card)

Cards

All permanents on the battlefield (
Gift of Immortality attached to
Contract Hero).

Activate
Ashnod's Altar by sacrificing
Contract Hero, adding ({C} magic symbol) ({C} magic symbol) .
When
Contract Hero 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
Contract Hero from your graveyard to the battlefield.
When
Contract Hero enters, it triggers, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({W} magic symbol) .
Cast
Gift of Immortality from exile by paying ({2} magic symbol) ({W} magic symbol) , attaching it to
Contract Hero.
Repeat.

This combo has been estimated to be Exhibition (Bracket 1+).