Underworld Breach | Frantic Search | Brain Freeze

(and one other card)

Cast
High Tide by paying ({U} magic symbol) .
Activate up to three Islands by tapping them, adding ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) .
High Tide triggers three times, adding ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) .
Cast
Brain Freeze for its escape cost by paying ({1} magic symbol) ({U} magic symbol) and exiling three other cards from your graveyard.
Brain Freeze's storm ability triggers, copying
Brain Freeze for each spell you've cast before it this turn, with one copy targeting you and all remaining copies targeting any player(s).
Resolve all
Brain Freezes, causing you to mill six cards, and each player to mill three cards for each
Brain Freeze that targeted them.
Cast
Frantic Search for its escape cost by paying ({2} magic symbol) ({U} magic symbol) and exiling three other cards from your graveyard, causing you to loot twice and untap three Islands.
Repeat.
Once you have milled your entire library, you may use the remaining ({U} magic symbol) to cast
Brain Freeze repeatedly targeting your opponents.