My upgrade order was Shards, Bucklers, Fahrenheits (at least, that's what I'd do next. I already had mine upgraded, lol), Lances, Firestorm, Towers, and then finally Rage Potions. I find that because it's a stall deck, and isn't at all
intensive, upgrading cards to reduce their costs (Bucklers, Lances, Firestorm) makes up for the Towers giving you that 1
upon being played, while also making them easier to cast.
But as TII said, this is just the very barebones deck. BatCountry has a VERY good version of it with only about 35 cards (at least, from what I saw in the Top50 a while back), and I've seen others with Sanctuary/Miracle, Antimatter, and even some Earth to splash PA.