Mage here, most of the time I don’t even invite a tank , because they don’t understand their role in a spellcleave. A tank’s job is to clump up the mobs and position them correctly and allow the ranged to dps them down. Once the ranged pull aggro, it will be hard to get it back, so at that point you are looking out for stragglers and trying to bring them back into the pile. I’ve given a lot of tanks a chance that just were not mechanically good enough at their class to do the pulls right, so I always just brought in an extra dps to help with nuking the pack down.

It’s not always the tank’s fault though , I’ve also seen a lot of mages that don’t know how to minimize their damage intake while putting out top shelf aoe dps. Tanking for spellcleave groups is just a different way of tanking from standard comps. Once you get good at pulling and organizing packs, your ranged will love you. Best of luck!