When Master Barrek sent this intelligence to the Jedi, a task force was assembled to destroy this operation. Commanded by Ki-Adi-Mundi, Tarr Seirr joined Jedi Master Shaak Ti, and Jedi Knights Aayla Secura and K'Kruhk to Hypori. It would be the last mission Tarr Seirr would take. The Jedi task force never even managed to launch an attack against the Separatists as their flagship was disabled while still in space and were forced to crash land on the surface. With battle droids rolling off the assembly lines at a constant rate, General Grievous had no shortage of warriors to throw at the Jedi. Surrounded by thousands of mechanized soldiers, Tarr Seirr and the Jedi had little choice but to hide in the wreckage of their ship.

Grievous slowly closed in on the Jedi and Jedi Master Daakman Barrek was one of the first casualties of the battle. Sha'a Gi followed Master Barrek into the Force and Tarr Seirr would be next. As Grievous pounced on the Jedi, he brandished two lightsabers to take on the five surviving Knights. During the battle, Tarr Seirr and the Jedi battle Grievous in the debris strewn about the crash site. As Seirr moved in to attack, Grievous used his talons to grab Seirr, slam his body into the ground, and fling it deep into the rubble of the ship. There was no chance of surviving such a ferocious attack. Seirr joined Master Barrek and his Padawan, Sha'a Gi to become one with the Force that day at the Battle of Hypori.