I don't say this often, but this comes down to a L2P issue. If they cast proxy, they need to wait a couple seconds to time the proxy det with the impact of toppling to output high burst, so if you get in their face right when they cast the detonation, you can attempt to stop the combo from being done, seeing as you cannot cast toppling at point blank range. But if you are dying to this combo without them even timing their proxy with their toppling charge I don't know what to say, might just need to like block or something, maybe just send in a ticket or uninstall because you just made a forum post about how you are dying to toppling charge and proxy detonation