On the EPC, TCF is bugged and doesn't interact with the weapons charged damage or radius stat at all. They don't interact with Persistent Plasma either, meaning T1C, T4A, and T4C don't actually do anything unless you completely whiff your shot. I'd recommend the path 21222.
The EPC's Tier 5A can enable you to light your sludge puddles on fire when you shoot them. If you fire a charged shot into it, not only can you light it on fire instantly, but the Persistent Plasma effect will stack with the corrosive and burning DoT for a total of 108 DPS. It's not a lot, but you can spread that out by a wide, wide, wide margin.
You can also try this tactic out with the Disperser Compound OC on the Sludge Pump.
