Ion cannons are energy weapons
and even sometimes ultimate weapons
, they are powerful and can exists in different variants from man portable cannons up to massive orbital satellites. They can fire Ion beams or Ion plasma like balls. Their effects may vary they can be highly destructive or even act like EMP weapons having a strong effect against shields and electronics and a low effect or practically no effect against organic targets.
When they are highly destructive, they can fire a wide beam that damages the aimed target and everything on the beam's path or fire a beam that causes a massive explosion upon impact that destroys everything in a large area.
When they are more moderately powerful they can fire a strong hitscan beam at very slow fire rate or even a slow moving Ion Ball.
Ion cannons can be fired normally when they are turrets or man portable weapons, but there is also Beacons and target painters to use them.
the Ion cannon is a man portable weapon and a beacon, the man portable weapon is an anti vehicle weapon, it fires a powerful hitscan Ion Beam and needs to be reloaded after each shot. The beacon in an other hand should be planted in the structures we intend to destroy, we need a few seconds to set them and leave the area; after little time it rains and large beam from the sky concentrates and destroys the intended structure and damage surroundings, the beacon can be defused by using the repair rifle.
In Earth 2150
the Ion canon is a sort of EMP weapon, it fires slow moving Ion Balls and is highly effective against shields and electronics, when an unit or a building is electronically disabled it can be converted by using repairers but we are unable to produce anything or getting any additional technology.
In UT 200X
, the Ion cannon is used via a target painter, it can be fired only in places where the satellite can target and it works only in maps where the satellite is present, the low intensity beam from the painter does practically no damage, but can be spotted by bots and players, when we fire it we should stay a few seconds with the trigger pulled to activate the cannon, otherwise if we move the cannon won't fire even if we maintain the trigger during the necessary time and more.
In classic Command & Conquer
the Ion cannon needs a building to be able to control the satellite. The weapon needs a delay to be charged up and once charged, we can strike any target in the map, the long chagring up delay forces players to think which target is better to destroy before engaging an assault in the enemy base or slow down the adversary by making a major impact to its economy / capacity to produce