It's doing 4k * Energy damage, where a full level counts as 100 Energy. Note they all start at level 1 so it's doing 4k * 100 = 400k damage right of the bat.
Pushing it to 60 energy in P1 makes it do 4k * 160 = 640k, going into P2 pushes it to 60 energy on level 2 (which is equal to 260) and makes it hit for 260 * 4k = 1.04M.
So, the least damage you can have is a level 2 static shock conduit with 0 energy resulting in a total of 200 energy (2*100 from the levels) which does 800k during the intermission.
Edit: This is for 10-man normal mode. Replace 4k with:
- 5.2k for 10-man heroic
- 6.5k for LFR
- 10k for 25-man normal
- 13k for 25-man heroic