hey,

can a peanut base figure end its movement with one base on the top of a set of stairs and the other at the bottom?

my guess would be no since the stair squares are only adjancent for close combat attacks

No they can not occupy two different elevations

Its one way you slow down Tiamat. Position on elevated so he has to either use his move and attack (-2 to attack value) or not attack since Charging upstairs means he has to fit his butt on elevated, too.