At the beginning of your upkeep, Assemble the Legion triggers, putting a muster counter on itself and creating a copy of Timestream Navigator with haste for each Muster counter on Assemble the Legion.
Activate a copy of Timestream Navigator, paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) and putting Timestream Navigator on the bottom of your library to take an extra turn after this one.