Illuminate lacks a traditional artillery unit. Using the Fistoosh against enemy vehicles is almost always a mistake: only the largest and slowest experimentals have even a chance of being hit by the Fistoosh's slow-moving missiles in combat. Instead, use the Fistoosh's high-power attacks against non-mobile targets: its range is large enough to allow easy and efficient harassment of enemy mass extractors and power plants, or bombardment of build structures or defenses.
The Fistoosh is quite weak in combat. Sent unescorted against even small numbers of enemy units the Fistoosh is an expensive failure. Protect your missile launchers with a mix of tanks and assault bots to draw fire and destroy foes.
Unlike its peers the Meteor and the Cobra, the Fistoosh has the added ability to hover, allowing it to bombard bases from the sea. It's range is rather limited in this regard however, forcing you to come close to the shoreline to hit what you want. At the same time, don't forget that simply moving away into the sea again will protect you once the enemy realizes what you're doing.
While you cannot usually use the teleport ability to perform surprise attacks as you would with the direct fire units, you can still use it to bypass blockades and also defensively to escape to safety if your launchers get attacked whilst isolated.
Use the teleport ability to get an automatic kill for a naval unit by sending units on different sides in groups of 5, and teleporting next to the naval unit before the units enter within the Fistoosh weapons ranges. This will almost guaranteea kill, because at point blank range the missiles have the same travel time as the illuminate tanks projectiles do at long range. These do extremely heavy damage, enough to kill a salem ship in 3-7 shots at the beginning of the game.