Try this. Wait till he spawns in on the warsat public event in the lunar complex. Make sure you have a full fireteam when you go. For some reason, his shields go down quicker in this fight. Have some one snipe him from afar with a good arc sniper rifle to get his shields down and then go at him with heavy machine guns with high capacity mags like harms way. I've killed him at least 5 or 6 times using this method. Make sure your sniper is good and has a high capacity rifle with a few special ammo synth packs, he can cover you guys and supply crowd control to keep the pests off you two while you focus on Urzok.

It took me like an hr of waiting to get him. First time I found him someone else got the kill before I could damage him, second time he smashed my butt because I was over zealous, and finally got him on the third try almost instantly with the Zombie Apocalypse maxed out I believe. So just hang out there and he will come to you.

Don't give up. Just keep popping in every once in a while and you'll eventually get lucky. I finally got him through a public event. JUST got to the zone as the sky went dark. I was the first to rush the warsat followed by a low level guardian. Shortly after, fellow higher level guardians appeared and we took him with relative ease.

If you need help killing him I'll help you tomorrow night I'm heading to bed. Just add me my psn is McSlap-a-Hoe.