璀璨火花 (Kyrian)
This is a flat damage increase, and is probably the one most players will end up taking as it just works in all situations (which makes it unfortunate that the Kyrian Signature Ability is by far the weakest compared to the shields, movement speed increases and teleports of the other Covenants). The low cooldown is great and the damage increase is of course useful. My biggest recommendation for
璀璨火花 is to make the debuff a longer duration, so that the spell can feel less rushed when utilizing
能量符文 and
火焰冲撞. Another concern is that different travel times on spells make it awkward to play ‘correctly’ and line up your biggest damage spell with the fourth stack.
折磨之镜 (Venthyr)
This spell will almost never get its full value in PvE, as NPCs rarely cast frequently enough to consume all three stacks, plus you generally want to be interrupting their spells anyway. The cast speed slow effect, while useful, makes proccing the root + silence at the end even less likely. In addition it appears to just simply not work on most PvE bosses, and in PvP begs to be dispelled.
死神之躯 (Necrolord)
Another contender for the default option, this ability has the advantage of having a use in cleave situations, although the cooldown is much longer than
璀璨火花. In addition,
火球术 and
寒冰箭 don’t deal a huge amount of damage anyway, so the Necrolord Covenant will be less attractive for these specs than it is for Arcane - which, again, pushes all Mages towards Kyrian.
It really confuses me that this spell affects
火球术,
寒冰箭, and
奥术冲击 when one of these is clearly not like the others (historically Fireball and Frostbolt are both used as "builders" to gain procs and contribute very little to your overall damage). Unless the spell is changed to make
炎爆术 cleave, it won't provide much more than just 10% spell damage which is hardly worth it given the cooldown.
变易幻能 (Night Fae)
Aesthetically this is by far the best-looking Covenant ability, but that’s where the attraction ends. Being forced into melee range is traditionally unhealthy for casters (we’re treated as valid targets for ranged mechanics no matter where we stand), and standing still for six seconds while the spell channels is even worse. Coupled with the fact that it only ticks every 1.5 seconds (so four instances of damage/cooldown reduction), and the cost of interrupting the spell becomes even worse. On top of all that, it’s only three seconds of Cool Down Reduction (CDR) with each tick, so just 12 seconds per full channel. With a 45-second base cooldown, that is a lot of channelling to make
变易幻能 worthwhile.