Mass of Mysteries + Prismabasher + Twinflame Travelers

Prerequisites

You have two or more opponents.

Steps

1. At the beginning of your combat phase, Mass of Mysteries triggers twice due to Twinflame Travelers, giving Prismabasher myriad twice.
2. Declare Mass of Mysteries (if able) and Prismabasher as attackers, attacking the same opponent.
3. Prismabasher's myriad ability triggers four times due to Twinflame Travelers.
4. Resolve a myriad trigger, creating a token copy of Prismabasher attacking each other opponent.
5. When the Prismabasher token(s) enter, they each trigger.
6. Resolve the first trigger, giving five creature you control +5/+5 until end of turn.
7. Repeat step 6 for any remaining trigger.
8. Repeat step 4 for the remaining myriad triggers.