Cateran Emperor: Why worry about Root Cage? Who's dumb enough to play it, when there are perfectly good Rebel Hosers to put in instead?
Also, I'm curious why you choose to use Terror over the Seal. I'm not really sure on the casting cost of Persuader, but if it's 4 as I believe it is, then you don't exactly have an overwhelming 3 cc slot, it seems like the Seal would fill that slot nicely, allowing for more varied removal than Terror. Furthermore, it's a Seal, generally a better choice than an instant in a deck reliant on saying 'at the end of your turn, I...'
Reasoning? Well, in a deck with a lot of normal permanents that don't require activation costs in mana, you usually don't have to worry about mana supply on your opponent's turn. With Mercs and Rebels, however, it's commonplace to have to search out a creature. That costs mana, so you don't often want to be saving two _more_ mana in case your opponent drops a big fattie on the table. Thus, you're better off with a good mana curve on your turn, and using Seals to 'invest' mana in for use at a later time.
Am I talking gibberish?
I'm not sure. I just think the Seal fits that slot better than Terror.