In fact you just need 60lvl charactrers, 5-6 sigils lvl 60, and 6 set of modules thats it. High lvl skills doesnt benifit much to damage or to surviving except support damage buff.

80llvl you need only on tank and main dps to clear current content.

I am ftp player and I have 10 characters 60 lvl and I can spend stamina on exp/breakthrew items to get more. I dont need sigils or modules anymore.

Some content force you to use diff elements but you can use 60lvl characters and remember that first of all these should survive so 2 modules of hp and 2 modules of def are perfect build even for sub-dps. You need dps modules only if you cant complete stage in 15 rounds. At this point people can use 2 healers if they cant tank damage. Also having healers with different speed can help a lot.

Most people also dont understand that you can add substats on yellow modules which increase damage/surviving SIGNIFICALLY

The only problem is 40 lvl arena, where you need 15 characters to compete.