Kill Rusty Cogsprocket (+2 level, even con) Use health items potions after Rusty Cogsprocket if at all possible. He will spawn a cog-work and not be able to take damage - try to kill him very quickly to prevent.
Kill Maldreya (again) (+3 level, one up) then STOP. Don't attack the epic. The stuns are for this fight - she will heal herself completely, repeatedly in the same fight. You will need to either be able to interrupt her every time or out dps her for 15 to 30 seconds until she dies. If you don't have stuns or interrupts, this fight will be almost impossible at level.
You can now either wait for Lucan D'Lere and Opal Darkbriar's conversation to end and speak to Opal Darkbriar; or you can exit the Temple and complete the quest.