An opponent controls two or more creatures that can be targeted by spells and abilities you control.
You have a way to deal noncombat damage to one of the indestructible creatures such that the excess damage doubled will deal excess damage to the second indestructible creature.
Deathless Angel twice by paying ({W} magic symbol) ({W} magic symbol) ({W} magic symbol) ({W} magic symbol) , giving two creatures an opponent controls indestructible until end of turn.
Deal noncombat damage to one of the indestructible creatures, dealing twice that much damage instead due to
Dictate of the Twin Gods.
Toralf triggers, dealing twice the excess damage to the second indestructible creature due to
Dictate of the Twin Gods.
Toralf triggers, dealing twice the excess damage to the first indestructible creature due to
Dictate of the Twin Gods.
Repeat from step 3 an arbitrarily large number of times.
Resolve a
Toralf trigger, dealing infinite damage to any target.
Notes
An example of the pre-requisite: If you give two creatures an opponent controls with toughness 2 and 3 indestructible, you would need to start the loop by dealing 4 noncombat damage to the creature with toughness equal to 2. This will deal 2 excess damage, which will be amplified to 4, thus dealing excess damage to the second creature and continuing the loop. It is recommended to start by giving the two smallest creatures possible indestructible and to target the smaller of the two creatures first.