This game gets hilariously broken after around floor twenty.
The best skill is Critical Strike. It takes into account both INT and STR in the multiplication. By the end of the game it was hitting for 60 times damage, with the best hit over 2 million.
Skills other than Crit lose effectiveness extremely fast, and even constantly spamming fire blast doesn't kill most enemies. Summon Skeleton is the worst, as it has a cap that loses effectiveness by around floor ten.
Charm is a good ability for the difficult floors 10-20. It takes an enemy off your back at the very least, and charmed casters heal you.
I found the best build to be Werewolf with all points into Stamina. Regen gets very high and allows for more time to react/run as the ability to fight larger battles.
Fantastic Game, the continual innovation by Undefined is truly phenomenal. However, as has been mentioned repeatedly there are a few minor flaws:
1) There is only one level of fast forward, so the game can get tedious on longer levels and slow waves. 3 speeds would IMO be ideal, with one ultrafast setting.
2)The loot system would be vastly improved with a sort option and, if possible, a larger inventory screen, most likely as a separate menu.
3) The awards, while very cool, are horrendously unorganized. It's difficult to find specific award types, so organization into categories such as *storyline quests*, *hire x amount of units*, *use skill X amount of times*, and etc.
4) More detail in the Protectorpedia. Many skills are very vague and questions are asked about stealing and consecration frequently.
If possible it would be great to see these addressed in some way in an update, but if not, they're just things to keep in mind for Protector V.