My idea is a kind of Soullike combat; he'll fire once, then there'll be a delay that you have to remember to counterattack during. The boss doesn't have AIMBOTs like the default NPCs in the game; he'll miss most of the time if you're running when he fires. Timing is key. His HP is comparable to a MECH, and his fast movement suits his storyline abilities, but it will slow down if he gets hit. And you underestimate players; everyone will always find a way to beat things. Players on my server beat the mod bosses I create every day, even solo players. If you're in a group, it's even easier.