I was having issues with the fight as well when I was standing in place too long so I adapted what I call flailing chicken kiting.
For the first part where Silvarre is down, I would start the wave with an AOE attack and have them chase me while I ran around in circles while picking off mages first and then the archers. This made the lancers less deadly as they couldn't do much against me.
This also let Leih AOE spam them and help me to pick them off.
For the second part, I ate vitality food so I could last longer as I knew the boss kitty was bound to have nasty attacks. I pretty much did the same thing as the first round and binded the lancers in place when I could.
I had taken blood for blood, second wind, cure, protect and stoneskin as secondary skills so I could kite them more easily. (I'm a Lalafell so I take damage easily hehe)
Maera, Mithra on Cerberus