Not sure if this was intended, but I found a rather OP playstyle that 1 hits the dragon. Basically just farm for golden hearts and buy a ton of items (mainly attack speed) and just instantly kills the final boss. Game was pretty fun tho :)
I was sure that was intended since it's not that easy to get. You need midas pretty early on to stack up enough gold to have for re-rolls. The whole fun of rogue-likes is finding these broken combinations and being able to finally get a good run with them.
The best combo would be getting midas and the burger early on, since the burger gives back gold heart meaning 2 gold so everything that cost 3 gold is now 1 gold each and boots are basically free. Spamming boots will stack up the damage of the shopkeeper dagger too so its extra damage.
Combine it with the bat fang charm and it's absurd, I killed the dragon in about a second, just buy only boots, mugs, and swords after you have the set up stuff and take the extra shots with the spellbook