Been running oracle entangle coc comet since league start and it basically destroys anything end game. Recently i did switch it to spark as iv been farming trials mainly.did not have to change anything on my tree since majority of my nodes are just crit and crit damage. I ran MOM eldrich and archmage. I use sacred of flame off hand. Its a 1 botton build aside from thrunderstorm just for shock. Iv killed pinnacle bosses in 5 seconds. I did use covenant robe for life leech. I tried the mana variant with coc and your mana basically bottle necks your comet. Life leech makes you coc proc non-stop. Just add fast metabolism on your amulet and either the acuity glove for instant leech or hear of the well diamond with instant leech atleast 12%. Just use bloodletting on entangle and life tap on your coc.