Quote from LoroeseAgainst multiple targets I expect shards to out perform prism because with enough targets you basically get AP saturated, i.e., you can't spend AP faster than you regain it. At that point Prism losed its effectiveness but shards continues to be useful.
Otherwise, prism and shards both scale about the same for multi targets and as long as you can gain benefit from the reduced AP cost of spells, I think prism will out perform shards. This mostly seems to apply to lower gear levels though, so those with really high crit, attack speeds, and APoC likely don't get more from shards, even single target. I haven't gottan around to simulating that yet though.
I have two sets of Chantodo's Will; one with a socket and the other with 3% Life Steal. With the one with a socket, I have 3.04APS, 55.5CC, 20ApoC and 225K DPS, and with the one with Life Steal, Only DPS goes down to 180K but I can use Shards instead of Shell(I should run Shell to deal with Reflected Damage)
I am wondering that 180K DPS with Shards 'might' outperform 220K DPS with Shell against 3 targets. Against a single target, for example, 180K DPS with Shards records 1min and 7 sec average and 225K DPS with Shell records 1 min and 5 sec average(MP9 Ghom)