Thinking of respecing Boomkins

[Ualaa]

With a Kitty...
You're not necessarily one/two shotting the entire group, but rather each mob one at a time... and they fall rather rapidly.
You do have Swipe as a Cat, but that's not often the best move.

Start in stealth.
Ravage a mob, which should outright kill it or put it very close to dead.

Stampede also allows you to Feral Charge Cat Form.
And then Ravage (Ravage is to Shred, as Ambush is to Backstab) without needing Stealth or having a positional requirement.
Predatory Strikes increases the crit chance of Ravage by 50% against fresh (over 80% health) targets.
Anytime you can Feral Charge Cat, you're basically going to kill that target (I believe there was a range requirement such that you couldn't use it on adjacent things, but could still attack casters who were a very short distance away from you).

The basic Kitty rotation I used was:
Mangle, Rake, Mangle, Mangle, Rip.

When questing against current level targets...
One Mangle (from Five Druids) dropped almost everything that was within +/- 2 levels of my toons.
That was in level appropriate questing gear.

When boosting, Mangle (and the Auto Attacks that follow) will drop most targets almost immediately.

Cat Form has a massive increase in DPS over Bear Form.
And like a rogue, you'll have a high amount of dodge (especially against lower mobs).
Bear Form has very high mitigation as well, but much lower damage.
Essentially, any time you can survive the mobs as a Kitty, go Kitty because they'll die in a quarter of the time.
But if you pull 100 mobs at once in Cathedral (SM), Bears will handle massive mobs much better.

Kitties have Stealth, Pounce/Ravage (both requiring Stealth), Sprint (Dash), Tiger's Fury (Energy Boost), Berserk (DPS Boost)...
Their Shred does more damage than Mangle, but requires being behind the target... while Mangle (boxed) is easier in that you can do it from any direction.
You can Rake (which is a combo point generating move) and Rip (a finishing move, which does more damage based on more combo points); these are both DOT effects, so the mobs armor essentially isn't there.

Bears have several survival options.
One reduces their Rage levels, but heals them as it does so.
And rage builds as they're hit.
Both have Survival Instincts, which is a health boost like Last Stand for a warrior.

If you have lowbies nearby, you could open with Hurricane as your pulling option.
That is AoE, so you'll have initial threat on everything.
But without spell power, it won't kill much if anything at all.
You could Bear Form - Charge, and then Swipe to hit things for threat.

[sync00]

When boosting, Mangle (and the Auto Attacks that follow) will drop most targets almost immediately.

I'm surprised you use Mangle when boosting. I use it with Berserk for bosses but stopped using it for large groups of mobs. When surrounded by a large group I can't tell what is targeted and I had facing issues with Mangle. So I just use Swipe.

[sync00]

I tried cat form but could not pull very well with the loss of health compared to bear form.