How do you gear your rift mage, ottffsse? I've found rift mage solo runs incredibly difficult in trespasser, with walk softly and even ground trials.
The thing with Rift Mage is that the specialization is built with teamwork in mind. The passives and spells of the Rift Mage is that of a controller and a debilitator.
Rift Mage weakens, debuffs and controls enemies, as such it works really well with a team.You slam enemies down, you pull them to a centerpoint, you smash them off their feet, you reduce their damage, you make status effects last longer on enemies and you increase damage done to enemies.
If you pay close attention, you will notice that Rift Mage does not have passives that lend them well to soloing. They do not have health recovery, they do not have barrier recovery and they most certainly do not have a second chance undeath passive that can be exploited to essentially be immortal. Put simply, Rift Mage is squishier which does not lend well to solos.
Yes you can solo as a Rift Mage but the other two specializations are far better for that. If you are looking to solo as a mage, Necromancer is your best bet though Knight Enchanter is the strongest against boss enemies with no Barrier Breaker.
I would actually go as far as saying that Cassandra and Solas are essential followers and the best followers for a Rift Mage Inquisitor. With both of them there you have 3 characters that can cause Weakness which means you can maintain almost 100% uptime for Weakness which gives you a whole host of benefits.
As for a Rogue follower, I would go with Cole (provided you enchant his daggers with heal on hit or guard on hit or waking fortress) because he lacks any ability that can trigger the Shock effect. Varric's Elemental Mines have electric mines and Sera has Flask of Lightning. You can avoid using those two abilities but they are good. Besides, Double Dagger Rogue has a high damage and if you spec Cassandra to be very tanky, Cole and get around and do some serious damage with Solas and Inquisitor providing magical offense and support.
Best Rift Mage Inquisitor Team :- Inquisitor, Sword & Shield Cassandra, Solas, Double Dagger Cole.