You could link two energy blasts and have time delay on the second, like this:
Cost
Power
END
29
Blob Gun: (Total: 65 Active Cost, 29 Real Cost) Energy Blast 6d6 (vs. ED), 16 Charges (+0) (30 Active Points); OAF (-1) (Real Cost: 15) plus Energy Blast 4d6 (vs. ED), 16 Charges (+0), Time Delay (+1/4), Explosion (Normal (Radius) -1 DC/1"; +1/2) (35 Active Points); OAF (-1), Linked to Energy Blast (-1/4), Lesser Power can only be used when character uses greater Power at full value (-1/4) (Real Cost: 14)
Powers Cost: 29