Derevi, Empyrial Tactician | Preston, the Vanisher | Panharmonicon

Cards

You control up to six permanents that can tap to produce at least ({1} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) .

Activate up to six permanents by tapping them, adding at least ({1} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) .
Activate
Derevi by paying ({1} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) , putting it onto the battlefield from the command zone.
When
Derevi enters the battlefield, it and
Preston trigger twice.
Resolve both
Derevi triggers, untapping up to two permanents.
Resolve the first
Preston trigger, creating a token copy of
Derevi that is a 0/1 Illusion creature token.
Put the nontoken
Derevi into your graveyard due to the legend rule, and choose to return it to the command zone from your graveyard.
When the
Derevi token enters the battlefield, it triggers twice, untapping up to two permanents.
Resolve the second
Preston trigger, creating a token copy of
Derevi that is a 0/1 Illusion creature token.
Put either
Derevi token into your graveyard due to the legend rule.
When the
Derevi token enters the battlefield, it triggers twice, untapping up to two permanents.
Activate up to six permanents by tapping them, adding at least ({1} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) .
Activate
Derevi by paying ({1} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) , putting it onto the battlefield from the command zone.
Put the remaining
Derevi token into your graveyard due to the legend rule.
Repeat from step 3.