[ The dice tower is such a time-honored tradition that Ford doesn't so much as blink when John swipes one of his sets for the sake of constructing one.

What does make him blink is when John specifically mentions a cross, since in his experience that's typically and specifically Christian iconography. It's something that strikes him as interesting and worth filing away for later.

For now, zombies are the more interesting subject. He's not surprised they have those in Willow's dimension, given some of the other things he's heard about Sunnydale. ]

Zombies aren't typically directed in our dimension. The spell I know just summons a whole horde of them that then do whatever they want - which is trying to eat people, usually. Losing control of them tends to be the default.