({7} magic symbol) ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) available each turn.
Steps
Cast Time Warp by paying ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) , granting you an extra turn after this one and exiling it due to rebound.
At the beginning of your next upkeep, rebound triggers, causing you to cast the exiled spell without paying its mana cost.
Activate Sanctum of Eternity by tapping it and paying ({2} magic symbol) , returning Venser from the battlefield to your hand.
Cast Venser by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , returning the extra turn spell to your hand.