I’ve played all 3 classes quite a bit and I can hopefully be of service. Warrior is mobile, but only when you have Intervene / Charge / Heroic Leap up, otherwise these boots are made for walking. Which means we have to be really picky when we use these abilities and, specifically for Intervene, whom we use it on (using it on the tank will usually lead to dying immediately). In terms of survivability, fury warriors really only have two tricks up their sleeve, and that’s Enraged Regeneration and Spell Reflect. Enraged Regen gives a flat 30% damage reduction and also makes Bloodthirsts during the 8 seconds heal for much more, around 25% max hp on a 2 min cooldown timer, able to be reduced by both a legendary and a conduit. Spell Reflect applies a 5 second buff that reduces incoming magic damage by 20% and will consume itself to either nullify or reflect an incoming magic ability back at the caster on a 25 second cooldown. Enraged Regeneration is rather straightforward, but Spell Reflect has a lot of nuance with it.
There are many mechanics that Spell Reflect works on and just as many where it doesn’t. Generally speaking because it’s such a low cooldown, it is worth just throwing it out any time you believe you’re going to take some magic damage and there’s certain mechanics that you want to make sure you Spell Reflect, and knowing which mechanics can be reflected and which ones you will just get the 20% damage reduction for comes with experience. Some examples from dungeons would be: Master of Death from Mue’zahla in De Other Side, Plaguestomp’s damage over time portion (not the knockback) from Globgrog in Plaguefall, and any targeted cast like Wicked Bolt from the Obliterators in Halls of Atonement can be spell reflected. It will take some getting used to, but my recommendation would just be to throw it out there and see what happens! Many players make the mistake of holding onto defensives too much when learning a new class, so throw it out there and make a mess! Very similar to disengage from BM Hunter, which I believe has the same or a similar cooldown. Opposite to Paladins, whose defensives are much stronger but are not able to be used nearly as often.
I hope that helps a little bit! I’ll keep an eye on this thread if you have any more questions about when to use abilities / defensives / offensive cooldowns.