Mass Effect 3 Vanguard Bonus Power?

I used the bonus power from Javik. The Dark Aura one.

For the record, I'm currently using Lash but I also like Reave.

Reave was delicious, especially with Liara in the squad.

dark channel? Once it kills the enemy it moves to another enemy. I've never used it.

the bonus power I use when playing vanguard. reave

Inferno Grenade is pretty decent on Vanguard. Can detonate with Nova or Charge.

Fortification is pretty good as well.

I start out with energy drain before charge is upgraded fully, then at the moment I've switched out to reave but I might experiment a bit with others.

What I absolutely won't do is go anywhere without Liara. Splosions... splosions everywhere.

Heh, I didn't claim that inferno grenades are an optimal choice; you are quite right about them being redundant as far as priming explosions and panicking enemies is concerned. However, the grenades do hit a wide area if the radius/shrapnel evolution is taken, so one grenade can set a mob alight. Also, they prime firesplosions on shields, which I have not observed incendiary ammo ever doing.

And they're just fun

Now I've ditched energy drain for reave, I'm experimenting with the arc pistol. I'm playing on hardcore atm - this is my first time playing all the way through with vanguard in ME3, so I'm still experimenting a lot, but I'm finding it very easy on hardcore so I'll push it up to insanity. As of yet (I'm at the point where I've just (re)met Jacob), there have been very few times when my squad mate's single overload ability hasn't been enough to deal with shields - especially since I feel powerful enough to just beat them down myself with nova and charge and heavy melee without taking too much damage. But since I've started taking along the arc pistol I find I'm using it far, far more than I ever did my assault rifle.

As it was, I tended to use Liara's powers frequently to set up cc with singularity, that I would then charge into, and obviously warp whenever it was needed (or when I just wanted to see some splosions), and was using my other squad mate's (mostly EDI until I got Kaidan back) powers infrequently to make sure overload was always available when I needed it. But with the arc pistol, I can use my 2nd squad mate's full range of powers more freely, knowing I've always got a way to strip shields myself.

I've never used the arc pistol before. It's fun.

I always take Flare. It's great for taking out those pesky engineer's before they can set up turrets, while I deal with other enemies.

Reave

I love using it as a one-hit kill in ME2 when fully upgraded, as it will completely drain most "red" enemies as well as disable them with pain.  (It can even weaken some shields well enough, too.) Reave works a bit differently in ME3, though, so I use it for all the glorious BIOTIC BOOMS and whittling down armor/barriers. Or sapping an annoying little baddy just because.

I've tried using Energy Drain to compensate for lack of tech skills, but, it wasn't as fun for me. I just bring a tech squadmate for that.

Energy Drain just feels so lacklustre. It would have benefitted from a bit more love on the animation/effect design front. But as a power, it's one that all classes can make very good use of.