Praise the Suns Light! (5e Optimized Character Build)
From D&D Wiki
Warning-This build uses older stuff from UA and up-to-date stuff from SCAG. Please talk to your DM before you try this. Also disclaimer: I did not come up with this, I found this somewhere else online.
This build works at about level 7 onward, where you take 5 levels of Way of the Sun Soul Monk and 2 levels of Undying Light (Edit" This is the Celestial patron ability) Warlock. After that there isn't much to say, but Undying light Warlock is much better than Sun Soul monk so you might as well just go 15 Warlock/5 Monk. Make sure your highest stats are (in this order), Dex, Charisma, Wisdom. When choosing Warlock spells, make sure to grab Hex. Now, Sun Soul Monks main feature is that it can fire off Radiant Sun Bolts that do 1d6+Dex mod. But with Undying Light Warlock, you also add your Cha mod because of Radiant Soul, adding a possible +10 to each Sun Bolt if your Dex and Cha are both 20. The reason this works is because Sun Bolts are "ranged spell attacks" and Radiant Soul adds Cha mod to any Radiant and Fire based spells damage. Now, remember Hex? Well, say you cast Hex on an enemy. Then, you fire off 2 Sun bolts (or 4 if your using a Ki point) will activate Hex every time you hit, and you will also do that extra massive damage with the Sun Bolts. So, hypothetically, with a 5 Monk and 2 Warlock, you can do 4d6+(Dex/Cha x 4) + 4d6. If we assume 20s in both Dex and Cha and that all four Sun Bolts hit with Criticals, the max damage is 88! It's a high damage build and also great to Roleplay. Have fun, munchkins.