Here is the full list of all 18 Tahira: Echoes of the Astral Empire achievements.
Complete the game on Wayfarer difficulty or higher.
Complete the game on Voyager difficulty or higher.
Complete the game on Leader difficulty or higher.
Complete the game on Princess difficulty.
Kill six units with a single use of Unbound Blast.
Kill six enemies with a single use of Light of Avestan.
Kill four enemies with a single use of Seismic Slam.
Send two or more units plummeting to their deaths with a single attack.
Kill 10 or more units with a Light Mercenary in a single turn.
Have a unit dodge at least 30 damage from missed attacks in a single turn.
On Leader difficulty or above, complete the game without Tahira ever taking HP damage.
At Barr'Aaid, have Baruti's HP drop to 5 or lower, and still win.
Complete the game on Leader difficulty or higher without losing a single unit.
Kill 20 units by knocking them off cliffs in a single play-through.
Overkill an enemy by at least 25 damage.
Have a unit die after killing 10 or more enemies in a single fight.
Kill at least 50 enemies from ambush in a single play-through.
Engage with every possible interaction in a single play-through.