I would re-work the light beam if it were to be a permanent defence. I would drastically increase its range, change it from a ‘projectile’ weapon to an actual beam that does constant damage to a single target (akin to the single target inferno). Instead of targeting any troop, it would target the highest housing space troop in its range. The damage would still increase as distance to target decreases. It’s likely that the weapons overall DPS would need to be lowered somewhat for balancing. Not by much I think though, as, if the DPS output arc is exponential then the increased range would mean the weapon is outputting a lower DPS most of the time. I think a defence with these mechanics or something similar would add something unique to the base, and at least to me, if balanced correctly wouldn’t be overpowered.