So played my first real game recently and thought it was weird that you can catch an edge of terrain and can chose to move into it, giving a sizable boost to movement in the right instance. Am I missing a step?

Example: my reanimates march forwards 4 and have a centimeter of their base collide with terrain that I can occupy, so I move into it, which makes them move forward by several inches.

Sure, you can get into it.

You may find moving out of it a bit trickier. You have to spend a march to do it, and you'll spend a turn with your back to the tile, meaning anyone who occupies it or charges in will flank you.

Everything in this game has consequences.

2 hours ago, Tvayumat said:

Sure, you can get into it.

You may find moving out of it a bit trickier. You have to spend a march to do it, and you'll spend a turn with your back to the tile, meaning anyone who occupies it or charges in will flank you.

Everything in this game has consequences.

If you are worried about being charged you could always shift out of the terrain, or stay in it and queue up a counterattack.

As others have said, when moving out, all you get to do is end up outside the terrain touching it, you cannot then move further without a bonus action on your modifier dial.