People talking in the world chat made me miss Stone Wall and I understand that it most likely isn't ever coming back and in part for some decent reasons .... like being uncleansable and in instances such as Death March being just thick enough not to be able to teleport through. Which got me thinking about recently seeing a single block stone wall spell (I want to say on the wiki) and thinking that would be great. Tho it still seems like it could be a little brutal. Then I remembered the door from Against the Cockroaches and all I could think was I want to be able to summon that! It would be almost like the warriors Force Field but instead of casting it on your mage you would cast it somewhere on the map to gain a temporary terrain advantage. Like forcefield it would only last X turns and either have a set number of attacks it could absorb or a fixed number of total hitpoints. Personally I think it it had its own hitpoints it would give it more weight. I was also thinking that it would be super neat if it was coded so that it was environmentally aware. So if it was summoned between two pieces of blocking terrain it would instantiate as a properly facing door but if it was summoned along just once piece it would be a pile of boxes or a lamp post or some such. Anyhow just thought that would be super neat
Reading the title made me think of the monster "Reinforced Door". I also know that they don't have any cards that summon new monsters but just extend existing monster groups (see spawn grub) or respawn dead characters (see reanimate).