The Monarch works best when allowed to fire constantly over extended periods. Starting out, its fire rate is slow, but after a few seconds of continous fire the gun turns into a hose of bullets. Continuing fire after reaching maximum fire rate will begin heating the gun up, causing damage to eventually turn from Physical to Thermal (this change is indicated by the Monarch starting to vent steam.) The gun cools off when it is not firing or reloading, and takes the same time to slow its fire rate as it does to increase it.
Due to how the gun works, a few variant modifiers have differing effects. Overclocking the gun improves how fast it will increase fire, with a 12 Overclock level reducing the time needed to 1.60 seconds. Tenacious will alter how fast the Monarch changes to Thermal damage in addition to improving its damage over time, with the gun switching damage types almost immediately when it is fully upgraded.
Like many other Aeolipile weapons, the Monarch is best used with an eye on defense, due to its time to activate fully and resulting immense fire rate.