In your opinion, what are the best attack icons? Aka ones opponents struggle to block.

Hehe, I use to have a spreadsheet with all the challengers and the icons they attacked with or blocked. Helped with building/revamping challengers. 100s of challengers added since then so not useful anymore.

I remember at one point, wind was not really blocked by challengers. However, there are so many challengers now with different weapons, I don't think there's anyone one icon that's better than another

Wind and magma were the hard to block challenger's attacking icons back in the day. Because they got around the Sanct and Cobalt spells. My how times have changed.

curse icons

...when the answer is so obvious you don't even think about it...

I put a variety of EoR on all my weapons to deal with any challenger and stack the curse icons

Haha i was hoping someone would be keeping track Like earth is pretty common, I thought maybe Magma or Ice derp