Clarion is nigh useless if you just, ya know, (1) nuke the mezzers, (2) mez the mezzers, (3) cc the mezzers, (4) let someone else aggro the mezzers, (5) pop a break free, (6) just wait out the very very rare mez that gets past (1)-(5) (likely with the tons of mez resistance buried in most IO sets) and god forbid you have to pop a wakie once every blue moon/solar eclipse/etc. If you do suffer a rare death as a result of mez, you probably weren’t popping insps, so you can combine several into a wakie/bf/green/blue and get right back up mid-fight. Ageless, Rebirth, and Barrier are just so much better.
Defense is helpful too I suppose.
And yes Clarion Radial has nice other effects but if you’re choosing the non-perma form of t4 clarion you really aren’t choosing it for mez coverage at that point.
Malta stun grenades are perhaps the only mez in the game that still feels like the bane of my existence once in awhile.