I did a faithful endgame mekuna build and capped out at about pit 120 doing maybe max 5 trillion damage, but while struggling to improve my build I looked at the tower leaderboards in-game and the pit leaderboards on the helltides website, and I noticed that the top players do different things
1.) They go meteor instead of familiar. More reliable overpower stacks. This was kind of a no-brainer but it's strange how it's not in the build especially when you have ring of starless skies.
2.) The biggest one: instead of godslayer crown, they use a crown of lucion charm. To compensate for the mana issues, they go lucky hit mana gain tempers on 2 out of 3 jewelries, with the other one being pretty much anything (cdr, crit damage, or even another lucky hit resource gain). They also take the perk that improves mana regen for every active blizzard. What this means is that not only is their damage increased by 90%, but they're using 150% more mana and therefore proccing the chain lightning enchantment that much more often too which procs on mana usage. When I switched, I went from 5 trillion damage at the most to 25 trillion at the most, and this is not counting the dps increase youre getting from all the chain lightnings. Go craft a crown of lucion charm and temper lucky hit resource gain.