Find the Chamber of Lies | The Temple - another visit Lords of the Fallen Guide

Definitely, the Tyrant that you encounter right after you enter, will be happy to see you.

After you enter the Temple, head towards the gate. Along your path, you encounter one more Tyrant. After you defeat him, pick up the Small key to the Western Antechamber (it opens the gate to the right of the stairs, at the bottom level [M3.34] - inside, a note and a chest (Eternal Legend - bracers, boots; Burden - a polearm)). A bit ahead (where there used to be the Blacksmith), watch out for the Mage.

In front of the gate, you will see a short cutscene and Yetka recommends you against walking into the arena (Eternal Flame) and suggests that you enter the Chamber of Lies. It is up to you, which path into the location you take - there is nothing in your way that would prevent you from defeating the boss in the first place and go to Yetka afterwards.

If you decide to fight the Protector, you can ask the Deserters to help you [M3.35] (as long as you helped them in the first place). They are staying at the Western Antechamber. If you encourage them to kill the beast, you will find their corpses in the arena (t is possible to collect the Human Tattoos then; otherwise you receive them also). You can then, give the tattoos to the Captain). The boss also has a bit more health points.