Ruined buildings, etc, do not always have stairs or ladders, so your warriors will have to climb to reach higher ground.

Any model (except animals!) can climb up or down fences, walls, etc. He must be touching what he wants to climb at the start of his Movement phase. He may climb up to his total movement in a single Movement phase (but cannot run while he is climbing). Any remaining movement can be used as normal. If the height is more than the model's normal move, he cannot climb the wall.

To climb, a model must first take an Initiative test. If he fails the test whilst climbing up, he cannot move that turn. If he fails the test while he is climbing down, he falls from where he started his descent (see the Falling section).