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,
Ajani's Welcome and
Cloudstone Curio trigger that many times.
Resolve all
Ajani's Welcome triggers, causing you to gain 1 life for each Dragon that entered the battlefield.
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
Demon of Fate's Design and any other creature(s) that were exiled by
Day of the Dragons enter the battlefield,
Ajani's Welcome and
Cloudstone Curio trigger that many times.
Resolve all
Ajani's Welcome triggers, causing you to gain 1 life for each creature that entered the battlefield.
Resolve all
Cloudstone Curio triggers, returning nothing to your hand from the battlefield.