It's an 'execute' - it deals up to 300% more damage when the target is under ?50%? health... Same family of powers as the night blade "killers blade" and the 2 hand "reverse slash", among others.
Take into account the amount of health left on the target, any debuffs, and whether the target is stunned or disoriented or knocked down or ensnared etc. In a pvp group, the radiant oppression is a great support power because a target is already battling and suddenly your beam hits like a semi roaring along without brakes, freeing up your ally and helping overcome any of those effects that trigger at the last breaths of health. Or you lay it on a fuller health target so it can be a distraction, pulling or splitting the target's attention away from your ally.
But make no mistake, due to the long channel time where you can do nothing but barely walk, it's definitely a support power. Archers can be a real pain in the arse, your beam is bright and you aren't a moving target, just begging for some poisoned snipe shots. Or for some stamina 2hander to burst in with a critical charge and animation cancelled wrecking blow / heavy attack / slice. Beware, prep stamina potions, maybe the invis ones from DB, and keep an eye on the far fringes.
Use it as a finisher, or when your opponent is permenantly roll dodging. It won't do much at full health on any competance player, and if you use it without someone there and they survive the first barrage, you're in for a world of hurt.
Some tips: Try to use it from safety, avoid channeling it repeatedly, and only use it when the fight is just about done.
Consider using Radiant Glory over Radiant Destruction:
-You are super vulnerable when channeling this, at least Glory heals you.
-Radiant Destruction scale off of your magicka pool.. Most time when they are in execute range, your magicka pool is far from full.
-The difference in damage is minimal. Seriously try it out. if you wouldn't of gotten the kill with Glory, you wouldn't of finished the fight with Destruction as well.
Learn to break the beam yourself (blocking), if you see his health going over 40% or you are in trouble.
Edited by sluice on July 6, 2016 5:39PM
PSN: sluiceqc (NA-PS4) CP: 551+ I strictly play on Daggerfall Covenant for when it comes to PvP
Depends on how properly geared you are. If you're leveling up a Templar then use it at 40% or below. If you're maxed out then you can start at 50%. Regardless of build though, if you're doing PvE and fighting a tanky boss then wait until the boss is at the 40% mark. In PvP though you can Dark Flare to Javelin to RO and with that short combo it kills 90% of the players out there.