But we will be choosing one, and though we can always pick another for our secondary spec and the option to respec for different encounters is always available, it's still important to know the strengths and weaknesses of each of these three AoE staples.
I already miss Arcane Bomb. Sure, as a spell name, Nether Tempest sounds just fine, but why mess up the symmetry of the bomb tier? We have Living Bomb, Frost Bomb, and ... Nether Tempest? This messes with my OCD something fierce.
Incongruous naming conventions aside, Nether Tempest is shaping up to be a really nice talent. When cast, it instantly places a powerful DoT effect on a single target that ticks out over 12 seconds. Each time it ticks, it does a solid amount of damage to its target but also picks another randomly selected nearby target and flings out half of that tick's damage onto it. And then the next time it ticks, it picks another target and does it again. So if the spell doles out 2,784 damage over 12 seconds to its primary target, it'll also be dealing 1,392 damage, spread out randomly over mobs in the general vicinity, over that same 12 seconds.
There's no limit to the number of targets you can place Nether Tempest upon, though the global cooldown and the spell's 12-second duration effectively prevent you from putting it on any more than eight targets at once, and doing that would require a constant rotation involving Nether Tempest and only Nether Tempest and nothing but. Like other DoT effects, the time between ticks is reduced the more haste you have, to the point where you can actually squeeze in an additional tick if you stack enough haste.
Strengths This is the spell you want in situations where you're fighting a single target, because it does slightly more damage to a single target than either of the other two bomb spells. It is at its best when fighting one or two targets, since it does excellent single-target damage, and the randomness of the secondary tick isn't an issue when it only has one other target to choose from. This is also nice when you consider that unlike the other two spells, you only need to have a single additional target within 10 yards of your primary target in order to get the max benefit from the spell. When your enemies are spread out, Nether Tempest is your best bet.
Weaknesses Unfortunately, Nether Tempest begins to fall behind the other two spells as your target group increases in size. Simply put, if you're fighting more than two targets, Both Living and Frost Bomb are going to put out better raw damage numbers.
Not much is changing about Living Bomb. Thank God.
It does on the beta what it does on live, namely, it burns the everloving hell out of everything in sight. When cast, it instantly places a 12-second DoT onto your target. Once that DoT expires, the bomb explodes, doing almost as much damage as it doled out during the previous 12 seconds, all at once, to up to three additional enemies within 10 yards. I would submit that those enemies had it coming, though, as they had 12 long seconds to get themselves away from the guy you just turned into a giant flaming fuse.
The DoT is affected by haste, and Living Bomb can only be applied to a maximum of three targets at once. Living Bomb has a 1-second global cooldown and is instant-cast, meaning that it'll take you 3 seconds to manually apply it to your three targets of choice. Glyph of Fire Blast allows you to spread Living Bomb with Fire Blast, which saves you a little bit of time and automates the process slightly over manual application.
Strengths Living Bomb is the best of the three spells whenever your targets number in the three- to six-target range. And in that range, it truly shines. It does rock-solid damage, and it's incredibly easy to use effectively. And the three- to six-target range, I would say, is the crowd size for which we use our AoE rotations most often.
Weaknesses When fighting a single target, Living Bomb is about equal to Frost Bomb but significantly worse than Nether Tempest. And Frost Bomb overtakes it once you get more than six targets. And though the damage does scale with haste, only the DoT portion of that damage increases. The other half of the damage, the final explosion part, is unaffected by haste. So while the spell will do more damage as your haste increases, it won't scale as rapidly as Nether Tempest will.
This is, in my opinion, the clear PvP choice. I'm not in any way implying that Frost Bomb isn't useful in PvE, but the snare component will absolutely shine in Arena or Battleground environments.
Unlike the other two spells on this tier, Frost Bomb has no DoT component. It does all of its considerable damage at once, after a 6-second countdown. You cast it on your target (after a 1.5-second cast time), mark him for death, and then 6 seconds later, he blows up, raining frozen chunks of mob flesh down upon the battlefield and serving as a grisly reminder to the other monsters that it is highly unwise to piss off the mage.
This explosion also deals half damage to every other mob within 10 yards. The spell can only be cast on a single target at a time and comes with a case cooldown of 10 seconds. Interestingly, haste reduces both the cast time and the cooldown of this spell, meaning as you stack haste, not only will you be able to cast it more quickly, you'll also be able to cast it more often.
In addition to the primary and secondary damage, the explosion also applies a powerful 70% snare to every affected target for the next 2 seconds.
Strengths Well, there's that snare. Any spell that can slow down multiple targets is going to get some use in both PvP and PvE. But because the damage can also effect as many mobs as you can manage to get together in a 10-yard radius, Frost Bomb does its best damage when you've got more than six targets. It does roughly equivalent damage to Living Bomb when fighting a single target, but as the number of targets exceeds six, it outpaces Living Bomb and blows Nether Tempest away.
Weaknesses Nether Tempest is still the better option against a single target, and in the three- to six-target range, Living Bomb is better. Unless you're fighting seven or more enemies, there are better options than Frost Bomb. Unless you need that snare, that is.
All in all, I like the design here. All of these spells have a clear role. They are each intended to be more or less effective in certain situations and have defined roles. Still, the gaps aren't wide enough to preclude any spell or promote any one spell as the consensus "best" spell. All three spells deal roughly equivalent single-target damage and are intended to be used in single-target rotations as well as in AoE situations.
No choice is good or bad here. You really can pick which bomb spell based upon which one you like most, and no one is going to question your choice. Well, someone might, but that someone would just be being a dick.
Every week, Arcane Brilliance teleports you inside the wonderful world of mages and then hurls a Fireball in your face. Start out with our recent beginner's guide to being a mage, then check out our three-part State of the Mage columns on arcane, fire and frost. Don't forget to look at some of the addons your mage should probably be using.