Well 2 blocks of C4 will no longer kill either a MBT or a lightning tank immediately. It just puts them into the red with about 60 seconds to fix it akin to the Sunderer . I'm not exactly sure what has been done to achieve this but from some quick testing in the VR it looks like its just an armour buff for the tanks vs C4 rather than a damage nerf for C4 in general. I would guess most of us knew that a C4 nerf was coming from all the tank driver threads on this forum. And at least for me this is better than I feared the nerf would be.