Ranger 4 (Gloomstalker), Monk 7 (Drunken Monk), Rogue 5 (Assassin), Fighter 3 (UA Brute, if allowed)
(RRR, MMMMM, RG, RG, RG, FFF, RG, RG, M, M, R) where R = ranger, RG = rogue, F = fighter, M = monk)
2 "normal" attacks, 1 Gloomstalker attack, 2 flurry of blows, action surge attack.
Alpha Strike: 26D6+12D4+2D8+42 (assuming surprise, auto crit, rolling with advantage on hit, advantage on initiative)
Also gives you a lot of speed, defense, utility, higher AC, higher Initiative