Can you believe it? Kekabu has no deadweight skills. All of them are useful. Kekabu is the zone boss of Arid Wilds. This is information I find useful when fighting Kekabu.
Weakness: Strike, Pierce, Holy
Anyone hit with this debuff will be frozen and receive 4x damage on hit. The radius is 30 feet, so the tank should try to dodge it when he sees the cast animation (blue aura and ice shards around kekabu).
Since this is a malice-clearing skill, the tank may lose aggro. If that happens, whoever has aggro should stall til tank gets aggro again.
The animation for this is too obvious. It's a giant circle on the ground with orange and pink/purple lines going around kekabu. Everyone but the tank can dodge this. This debuff is removable, so healers should remove it unless the tank needs cures.
This is a stacking heal, which means if kekabu recasts this before the duration of the buff is up, the heal amount per second grows. If you stun kekabu when the buff has 5.5 seconds left on duration, it will prevent him from stacking his next heal. This will greatly hinder its effectiveness. I am not the one stunning in this video; check out the Abby section of <STEP's Guide to Rotten Bosses> for info on the stun timing.
Also a good thing to note: Engineers and Hunters shouldn't have to worry about moving too much like Giles; shots and range skills keep it out of this bosses largest AoE.
As for the Blue Blizzard skill that freezes, Engineers or assigned person that stuns, don't be afraid of helping out the tank when you see him/her lagging on running. Unless the boss is at <20%, you should time your stuns to help out the tank, a good example being when the tank loses aggro.