Artillery shells deal splash damage, so if two or more buildings are adjacent to each other, an Artillery shell can deal its full damage to all of them if directed at the center of the building cluster.
Artillery can be used to "mark" targets for smokey Zooka attacks on defenses in Operations. Provided that no other targets in range are more severely damaged than the marked target, the Zookas will act to attack the marked target(s) first if a Flare is not used. A similar strategy can be used to target particular buildings when using the Universal Remote.
Do not place buildings adjacent to each other, not even adjacent at a corner, as they can all be damaged or destroyed at the same time.
Upgrade defenses that are common Artillery targets to increase their health. If a defense has a lot of health, an attacker will have to use more energy to destroy it. Building Health Statues can also be used for this reason.
There are no visual differences between upgrades. However, damage increases by 11% with each level.