Using varistors to protect a DC circuit

Hello, I am currently toying with some ideas for a motor controller and I have decided I want to galvanically isolate the high and low sides of a gate control circuit via a capacitive isolation. At the gates though I still need a voltage limiter of some kind and I was thinking of tying a varistor to each gate lead so that they short toward whatever side of the bus they are on. If they are high, they short high, and if they're low they short low. This will put all of them in the OFF position(enhancement P-channels up top), and hypothetically should stop voltage spikes from frying my transistors.

The main problem is that I've never used them before and want to make sure I use the correct parts. The circuit is DC and I assume I need to buy them based on their expected DC voltage yes? Is there anything I need to know when implementing these?