Because the low level ones "solve" the game too well. If you play Warlock you just Firebolt your way through every opponent. And if any class takes Icebolt at level 2 you basically never have to think about your action cycle at all.

Why nerf low level bolts though? The game is hard enough in the beginning as is

'nother update. Turns out that enemies use all the same skills the player does, so I'd accidentally made Human Wizards and Elven Spellsingers *terrifying*. Which, while it was very interesting to play, probably wasn't good for overall balance. Now, AI goes back to using vanilla skills, players get changed skills. I personally really like the way the changes have fallen (even though in my own games I haven't actually gotten any of the mid/high level Bolt skills to see how they feel)

Please let me know what you think of the balance changes! Also, if I missed any Bolts, or if their new values don't match their intended values listed on this spreadsheet: https://docs.google.com/spreadsheets/d/1OOEq77Ns-0lW4kh7SOS7eaCajGbueK3Ny4tFQnv9YDw/edit?usp=sharing