({11} magic symbol) ({R} magic symbol) ({R} magic symbol) plus enough mana to pay for commander tax, if applicable available.
Steps
Cast
Leashling by paying ({6} magic symbol) .
When
Leashling enters the battlefield,
Dual Nature's first ability triggers, creating a token copy of
Leashling.
Cast
Etali either from your hand or from the command zone by paying ({5} magic symbol) ({R} magic symbol) ({R} magic symbol) plus commander tax, if applicable.
When
Etali enters the battlefield, it,
Dual Nature's first ability and
Cloudstone Curio trigger.
Resolve the
Cloudstone Curio trigger, choosing not to return anything to your hand.
Resolve the
Dual Nature trigger, creating a token copy of
Etali.
Put the token
Etali into your graveyard due to the legend rule.
The token
Etali and
Cloudstone Curio trigger.
Resolve the
Cloudstone Curio trigger, returning
Etali from the battlefield to your hand.
When
Etali leaves the battlefield,
Dual Nature's second ability triggers, doing nothing.
Activate the nontoken
Leashling by putting
Etali on top of your library from your hand, returning
Leashling to your hand from the battlefield.
When the nontoken
Leashling leaves the battlefield,
Dual Nature's second ability triggers.
Holding priority, activate the token
Leashling by putting
Leashling on top of your library from your hand, returning the token
Leashling to your hand from the battlefield.
Resolve the
Dual Nature trigger, doing nothing.
Resolve the token
Etali's trigger from step 8, causing each player to exile cards from the top of their library until they exile a nonland card, and allowing you to cast the nonland cards without paying their mana costs, with you casting
Leashling from your library.
When
Leashling enters the battlefield,
Dual Nature's first ability triggers, creating a token copy of
Leashling.
Resolve the nontoken
Etali's trigger from step 4, causing each player to exile cards from the top of their library until they exile a nonland card, and allowing you to cast the nonland cards without paying their mana costs, with you casting
Etali from your library.
Repeat from step 4.
Results
Cast all nonland cards from each opponent's library.