Re: A little help
If knocking people down is the primary desired effect, you might want to throw Double Knockback (+3/4) into the mix. If my math skills haven't failed me, you end up with:
7u___"Hammer Time" 6d6 EB (Physical), Explosion (+1/2), Double Knockback (+3/4), Personal Immunity (+1/4), Only Affects Targets in the Ground (-1/2), No Range (-1/2).
On average, this would give you 12 'BODY' at Ground Zero from which to calculate KNB, as opposed to 8 'BODY' with the straight 8d6.
If all you were interested in was knocking people down, you might also slap a Does No STUN (-3/4) limitation on it. That saves you two points!