Phainon is my favorite character to use in CW, so I tried to unlock his full potential.
The way he works is that he gets bond effects from his on-field teammates. The best bond that takes advantage of that is Galaxy Ranger, which gives Phainon a ton of DMG and SPD amplification based on Galaxy Rangers star level. This strategy is viable in normal runs and can be done if you manage to upgrade all Galaxy Rangers to 2*. Getting multiple 3* galaxy rangers is possible, with a bit of luck.
Phainon also gets stronger with higher star levels of on-field teammates. It's hard to fully take advantage of this in a normal run (Galaxy Rangers need to placed off-field to get their buff, except for Ashveil).
Getting SW 999 solves that problem. With the money that SW provides it's easy to get all characters at 3* level, starting with Cyrene. She also gives a huge damage buff, 6 Day and Night Demigod emblems. Her poems are also very useful. The best ones are:
Raise Eidolon level by 1 (My Phainon is E1, so with that he becomes E2. If you manage to get Gold Investment that does the same thing, it's possible to get trial Phainon to E2)
Get a basic weapon box (useful for making emblems)
Get a Day/Night Demigod emblem
Get an emblem codex
SW 999 also gets you 3 diamonds, 3 red and blue gems, 99 furnaces and golden wrench (which has unlimited uses)
With Cyrene's emblems I maxed out Day and Night demigod bonds, and by making and rerolling emblems I maxed out Express Cohort and Planet of Festivities bonds. Giving emblems to on-field characters lets Phainon get its bond effects, so I didn't need to put Sunday on-field for Penacony bond.
And that bond is extremely busted because at max level it increases on-field/off-field strength by 44% for EVERY emblem that you have. It results in a massive increase.
SW also gives golden cards for item upgrades, so I managed to get Golden Trash Bag and upgrade the rest of the items.
After all of that, Phainon's on-field strength in battle almost reached 24000, SPD amplification reached 1210% and DMG amplification was at 956%. Khaslana's meteors hit for more than 100 billion damage.