I've done ten rooms and haven't seen a single room upgrade medallion

either bad luck or whoever dropped 3 in a run is lying to you.

good thing i have 12 tier III spymaster before the nerf and half the temple is secured. but it's impossible to build new spymasters now on a longer chain.

spymaster is different, it can only be level up by medalion and sacrifice/remove another spymaster, so you need two spymaster card(unless there's an exsiting one on other chain not protected, one sacrifice card (so need a secrured sacrificial chamber, because you can't guarentee the next close temple will remove that other spymaster card), and a upgrade medalion AT THE SAME TIME to be able to put down a tier III spymaster and lock it. Also need all other spymaster already tier III so this new one gets the level.

also i'm getting 4-5 rooms destroyed after every run, so idk who said it's 1-2 rooms, but not in my case. maybe when you dont have many rooms yet.