Iron Will Cascade questions :)

Hello!

I have some questions about my build, its Iron Will Glacial Cascade. The Question is how to i effectivly stack up damage ? My first thought was i do added light + herald and try to get shock aswell but i dont think iam able to shock bosses later on without shock nodes... so My question is how do i scale up my dmg ? Iam usen a 5L atm GC-Echo-added light dmg-controlled destruction-iron will iam arround 11.5k dps with heral of thunder on. Also i use blasphemy with ele weakness !

Heres the tree: https://www.pathofexile.com/passive-skill-tree/AAAAAwUA-d2LjMCaCarZ_MBmPAUEs5_f73yiAJo78B_tPIKbaPLVpuw45CI62IV7GmwnL2ZUNumQVSSqGjgWb1nz42pyD3GF8xGxQqyqcqlVqZe0agHE9sauPC2DzLc-QYf56P4K2L33MuoYdqzPfq2N-OsUcdl8ggfyQfPdaGXSIZ7NVbXBBF8_FCDvDlBH9kiMzz38WGPG2EVHMtHr7prgRZ1TUnyDES0snCt4H8cti20Zl_RSUz1fl5UI9MBUakO86q-nHM4rUA3N_lQ=


I hope you guys can give me some advices ! thanks alot !

I'm not really familiar with iron will builds but i think with non-crt GC you won't get much scaling or shocks. (so reconsider added lighning damage)
Also, check your dps again when your gems are lvl20 q20.
Also, try using
http://pathofexile.gamepedia.com/Repentance (and replace the iron will gem)
http://pathofexile.gamepedia.com/Doon_Cuebiyari