Day of the Dragons | Demon of Fate's Design | Enchanted Evening (and two other cards)

Cards

Cast
Day of the Dragons by paying 7 life due to
Demon of Fate's Design.
When
Day of the Dragons enters the battlefield, its first ability and
Cloudstone Curio trigger.
Resolve the
Cloudstone Curio trigger, returning nothing to your hand from the battlefield.
Resolve the
Day of the Dragons trigger, exiling all creatures you control and creating that many 5/5 Dragon creature tokens.
When the Dragon(s) enter the battlefield,
Cloudstone Curio triggers that many times.
Resolve all but one
Cloudstone Curio trigger, returning nothing to your hand from the battlefield.
Resolve the final
Cloudstone Curio trigger, returning
Day of the Dragons to your hand from the battlefield.
When
Day of the Dragons leaves the battlefield, its second ability triggers, causing you to sacrifice all Dragons you control and return all cards exiled with
Day of the Dragons to the battlefield.
When the creatures that were exiled by
Day of the Dragons enter the battlefield,
Cloudstone Curio and
Verdant Sun's Avatar trigger that many times.
Resolve all
Verdant Sun's Avatar triggers, causing you to gain life equal to the collective toughness of the creatures that entered the battlefield.
Resolve all
Cloudstone Curio triggers, returning nothing to your hand from the battlefield.
Repeat.

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