He doesn't summon adds. Instead he uses the spell Total War which causes him and all allies fighting alongside him to blitz one target (maybe? hard for me to tell because he spawned for me at a spot where I can't split him from several other mobs and my puller dies pretty much instantly from all the stacked damage). You will see this reported in your spell log as "Tactician Crucidon casts Total War" followed by the damage inflicted, up to 25k, followed by every other mob he is fighting alongside having the same cast line and damage infliction. This means that damage from Total War is multiplicative depending on how much assistance he has.
He has spawned at Catapult 2 several times, but apparently he can spawn many places. Like alot of mobs in Argath, if you just run around killing ph stye mobs, you could see a named anywhere.
I usually camp him at cat 2 for the possible spawn of the 2nd named who can appear there.