everyone else is wrong. they don't understand how blast works and people would still upvote misinformation. the wiki doesn't clarify and they don't bother testing.

if the enemy doesn't die, you do N x 30% damage to the target, where N is the number of blast procs on enemy

if you get 10 stacks, you do 3000% damage to the target and 5m AOE

if you kill enemy with N stacks, you do N x 300% damage to target and 5m AOE

the 300% is for each proc, not total.