Which capacitor for a high current resonant system?
Just for starters, at 100 kHz, a 2u2 cap will have an impedance of 0.723 ohms. With 70V p-p applied (sinewave) the RMS voltage is 25 V and therefore the current is 34A RMS.

You should be looking for capacitors that are COG/NP0 - these have the lowest losses and maybe you can get away with X7R dielectrics. You might also consider increasing your coil inductance by a good margin so that the capacitor values are reduced and fewer parallel caps are needed.

I don't know how you are winding your coil but I'm guessing you are using Litz wire to avoid high resistance losses in the coil.

As a side note - I've used a bank of 100nF ceramic COG/NP0 capacitors to run at 12A RMS in parallel with a single large coil for a metal detection product. The tuning was very important - it had to stay stable and these sorts of caps are the best.