[GameMaster]

Zombies are pretty unstoppable. They're slow but can pretty much get through anything. Your best bet with zombies is to create a flamethrower like device. Some hairspray and match or something. Once they're all burned up they can't do anything.

Now with mummies, I don't think water would work. The worse that could do is just ruin it's outer wrapping. But the body within would still be fine. With mummies you either need to read out loud a spell so the mummie will be taken to the afterworld (like in The Mummy movie) or light it on fire just like the zombie.

And I think the reason both are so slow is because generally their bodies are pretty old and have begun decomposing so their joints and bones and stuff aren't going to work as well as they did when they were living.