they do little knockback upon initial explosion, spamming out several shards that lay on the floor forming a 'ring' and those shards explode. extreme small radius, then near obstacles shards wont spawn.
more shards are spawned as the grade increased, 8 shards for 5* i think.
seriously fiend killer? how can such a tiny ring kill fiends, DBB or even proto bomb does the better job.

the original shards can be used to snipe fiends and of course kill them. still rough but its ok.

It is easier to dodge and run away from projectiles when you have 3 bars+

But for me, as Aussie with 1 bar it's just painful and awful to deal with fiends, I need to predict their attacks, estimate the time they attack and do the maths quickly in my head in order to shield and block their projectiles.

Here is my way of dealing with fiends as a bomber, I'm officially a gunner xD but I own, or used to own all bombs, I've tried all of them an figured out a 'way' to deal with fiends if you are in the latency zone.

Just use AoA, see them burn, burn to death. I ususally crown fiends, plant AoA as I run. Using electron vortex might sound like an efficient way but that doesn't work for me, I can't shield at all.

My solution is: Fiend levels, get in a team, bring electron vortex and toothpick. Team mates will deal with them. I just plant bombs and toothpick if necessary.

Few tweaks:
Make this a new line of bombs
give back RSS
Make damage worth it
Fix the stun bugs
make it a mine that when stepped on after the pblast and releases the charges, upon being stepped on explosion. they last for 7 seconds until they fizzle.
Buff the hell out of it for the damage

i got all blast bombs, 4* heavy decon my favourite, then comes BAB, so cute xD