Wall - one point wonder, or worth investing?

[Akimbo]

Well I'm a little dissapointed with the skill, as it's treated as one entity, meaning it can be destroyed very easily. It's a shame it's not like the Ice Prison skill from the first game (Was called Ice prison or something similar...been a while, hopefully you know what I mean, it was cast from the Rage Box 3rd spirit.) which despite having like 1hp per section, was still made up of ~8 pieces.

I do still like wall, it's great to be able to hold off a unit for a turn at least (near the start of the game) or to use it to encourage the AI to take a narrow route through the battle map (though sometimes they will plough through if the alternate route is blocked by their own pieces), however is it really worth investing in? I get the feeling later in the game it'd probably not take many hits, if more than one even with points invested in it. So is it worth just keeping it at level 1? It'll still soak up a hit, but is cheap and somewhat spammable. What are experiences of it maxed like? Does it survive multiple turns end game or not?

At the moment I'm using it against weak enemies I intentionally ignored earlier in the game. (I'm just at Bolo now, a little underpowered maybe but not a problem.) I kill off all the enemy, except for one unit, which I get as small as possible. Then within the first 10 turns, I spam as many stoneskin spells and shield spell (from Archmages) as I can, while doing everything possible to block the last enemy. As you can guess I'm trying to work through the damage reduction medals asap. However what prompted this post, was that soon I feel that Wall won't be able to help me with this tactic. So I'm getting as much out of it as I can while it's still possible.