For Castrum Meridianum, there is a lot of mobs, but some of them can disappear. Unfortunately, lately I have seen groups choosing to grab them anyway. For instance, at the start, there are two lights that can be shutdown to make some mobs disappear.
At the start: grab mobs, (let people turn the lights off), run with the mobs to the boss line (without crossing it or a cutscene will pop) and kill them all.
First boss: focus boss, grab adds if OT. Boss should die quickly.
Then, climb up and stay close to the wall not to aggro the soldier on the magitck armor. Then run to the next pack and turn the light off.
You can pull the mobs until the colossus.
There is nothing special until second boss.
For the second boss, as the MT you can tank it where it is and you should not bother with the adds, that's OT's work. The norm used to be to tank it close to the exit door so that you can grab the magiteck armor and some adds as soon as they pop (to help the OT).

After that, it's always the same, grabs mobs, let them be killed by the cannons.
Third boss, nothing special.

Go back to cannons with mobs.
The last phase can be a pain because not everyone wants to kill the mobs before the last boss with the cannons. What it used to be was: grab the collosus back to the cannon.
Go back to the door with the army of mobs, climb the stairs on the right, pull the mobs up there to the cannons. Meanwhile, the other tank will turn the light off and go up to the second stairs and pull back the mobs to the cannons.
First tank will turn the lights off upstairs (second staircase). Then pew pew with the cannons to trigger the cutscene. 2 or 3 collusus will pop, either you bring them back to the cannons or you kill them where they are.
Last boss should not change much. Remember that whoever has hate should stand in the center of the room for the cannon part.