i got my endless 30 achievement the first day, so i can share some insight. i did it as SV with CTHC, binding, aoih (though that doesnt matter), fervor, blink, and barrage. i used standard raiding glyphs, but they didnt provide too much use.
use flask and food, they help quite a bit. remember, your gear gets scaled down and set bonuses/legendary cape proc/legendary meta proc are suppressed.
the way rounds work - they are always the same, and there are only 10 rounds, after the large sha (round 10), the pattern repeats. knowing what mobs spawn and having a strategy for each round is absolutely key.
i try my best to start each round with a trio of traps down, with certain exceptions. on round X7 (the one with the mystic and 2 dummies, that spawns 3 exploding spirits), i save my ice trap to proc lnl when the two back-to-back large spirits spawn.
as SV, you want to use serpent sting to your advantage, throw it up on multiple mobs and try your best to refresh em. at the very least it'll knock some hp off.
I save personal cds for round X0 (large sha), and i use the zerking buff they give you on rounds X7 and whenever i feel i need it based on 'oh !@#$ moments'. sometimes i have to use them on round X6 (the 2 amber shaper and shield and banana round), but sometimes i get to save it and use it to zerg X8 or X9.
otherwise.. i use binding shot on round X2 and barrage/multishot before the banana guys leave the center, to get a nice stun on them and they die pretty quick after that. i tend to use binding shot to stun the banana guys whenever i can, on any round.
on any rounds with amber shapers and shield guys, i follow the pattern where i get the amber shaper to stun one (and they take increased damage) then dps it while i move to the next one, so that the next amber glob goes to that one while i dps the first down. you get a nice rhythm going, and it clears the round faster.
on the round with TWO amber shapers, i frost trap one and then continue my pattern while keeping SS up on the first amber shaper, when it dies i break the other one out and continue the strat.
on rounds with healers, i take them out first and interrupt their first heal, they are dead long before number 2.