Artist of War
To complete Tier 7 and getting enough shards to promote your Thrawn to 7*, you will need 5 7* Phoenix characters. Gear Level 9+ and good mods are recommended, while Gear 8 is the “bare minimum” with excellent speed mods. Omegas on Uniques and Hera’s lead, as well as on other important abilities are mandatory. No zetas are necessary, but can make the event much easier and lower the gear and mod requirements.
The recommended team to use is Hera Syndulla, Kanan Jarrus, Ezra Bridger, Chopper, and Garazeb "Zeb" Orrelios. The first 3 encounters of the event are very easy, provided you have sufficiently geared Phoenix. Try to save all special cooldowns for the final encounter. Dispel the Stormtrooper (Tank) at the start of the encounter. Use Stagger or a Dispel to get rid of the “Deadeye” buff on the Death Troopers. Taunt with Kanan or Chopper, and use Backup Plan to survive Fracture. Try to Stagger, Stun, and Expose Thrawn when possible. Kill Order is Death Troopers > Stormtrooper Commander > Stormtrooper > Thrawn. This event takes a lot of RNG with low gear, but this strategy should help you beat it eventually.