Well, I didn't actually lower their damage, I only lowered their spawn frequency. If you're still having trouble advancing, lemme share a couple tips:
- Instead of going for large groups of the same color, focus solely on making as many single rows of 3 as possible of different colors. This increases the color damage multiplier by a lot; just 4 different triplets will already bump your damage up to 1000 (1200 with Robust Quercus equipped).
- If you do opt for making larger links, try going for X, L, or T-shapes, as they're rather easy to make without disturbing any other gem combinations you may already have on the Gem Tray. Trying to connect ALL gems of a single color on the tray should only be done if you require a huge bolt to deal splash damage, but keep in mind that you likely won't have any gems of that color in the Gem Tray anymore after calling that bolt down.
- If you're playing with the Furious Fuchsia jewel, save the ability up to destroy the high HP tank units (Frugards, Frustems and Fruborts). If Fruquark shields are bothering you too much, consider using the Icy Indigo jewel, as its freeze ability temporarily removes them.
- Try starting a dummy game one time just to experiment with matching gems and trying out different combinations, or to see just how strong of a bolt you can create! It may take a minute or two, but you can end up with 3000+ intensity bolts! (possibly even higher with Splendent Silverfir if you want to go that route, although it's not really a beginner-friendly staff)
Hope this helps a bit! Good luck!