Fire Nation Archers by paying ({5} magic symbol) , dealing 2 damage to each opponent and creating a 2/2 Soldier creature token.
When the Soldier enters,
Mana Echoes triggers.
Holding priority, activate
Fire Nation Archers by paying ({5} magic symbol) , dealing 2 damage to each opponent and creating a 2/2 Soldier creature token.
When the Soldier enters,
Mana Echoes triggers.
Resolve the
Mana Echoes triggers from steps 2 and 4, adding ({C} magic symbol) ({C} magic symbol) for each Soldier you control.
Activate
Fire Nation Archers by paying ({5} magic symbol) , dealing 2 damage to each opponent and creating a 2/2 Soldier creature token.
When the Soldier enters,
Mana Echoes triggers, adding ({C} magic symbol) for each Soldier you control.
Repeat from step 6.
Notes
The starting mana cost assumes you control no other Soldiers when starting the combo. If you control more Soldiers, the mana needed is as follows: ({10} magic symbol) for one Soldier, ({8} magic symbol) for two Soldiers, ({6} magic symbol) for three Soldiers and ({5} magic symbol) for four or more Soldiers. If you control two or more Soldiers, only perform steps 6 through 8.