For once, it wasn't Rex's clone that was the strongest here.
He was here to provide support when needed, exactly as he did against Shadow earlier.
It wasn't him who was going to be doing the heavy lifting, this battle relied more on Gistella, Adhara, Flunra, and the Alpha Primes. Each one of them was stronger than Rex's clone, that was why they were the ones handling Shadow earlier.
Valkis and Fenrik were nearby, stuck dealing with the Undead Revenants.
Mavok was also behind, he was the latest to arrive.
Flunra was nowhere to be seen but his scent was around so he must be nearby.
And on the frontline were both Adhara and Gistella.
Rex's clone got lucky and was able to destroy one of the towers, decreasing the pressure on their backs. Now the duo could charge ahead, and reach Zal'karn as well as the Death Order Stones obelisk behind him.
His role now was to keep decreasing the pressure on them so they could advance.