The Lemonicus is a boss that was added on the 10/18/2020 update. Lemonicus spawns as of the 10/27/2020 update.
Lemonicus has low speed and a medium amount of health. Its auto-turrets are not very strong but still decent, have a medium rate of fire and penetration. Its paralyzer turret shoots at a slow rate, but has fast and strong bullets with high penetration.
Spawns by randomizer.
Lemonicus has a mediocre firepower, but it's paralyzer turrets is very dangerous. Lemonicus does not represent a threat if you have decent firepower until you get paralyzed. You should dodge this bullet and keep a medium distance to not get paralyzed. If you are paralyzed, focus on eliminating incoming bullets and going back to dodging again. If you move in a left-right pattern and shoot at the boss, you will eventually be able to kill it.
There is also another way of killing Lemonicus - utilizing it's large size. A good way to kill this boss if you have poor firepower is to attract it near an obstacle, whether it be a maze wall or rock. Due to its large size, Lemonicus will just get thrown aback when approaching a tight space, so a maze wall or two tightly packed rocks are ideal. Find a position where Lemonicus cannot hit you from the obstacle, but you can hit and start firing. Boss will be dead quickly this way.