Based on the Elder scrolls online fort capturing system, i'd like to see Attack on a well built base consist of the following stages, I do understand that players will find ways to use them in ways they were not intended though.
Siege
Use long range artillery (Slow/Stationary, Large energy use/Heavy ammo) to take out perimeter defense. (Only damage certain structures, turrets/boosters/nodes maybe to prevent being used to destroy or put major non-defensive structures into reinforced/destroyed)(Maybe requires target painters to see from a distance and can't be used at close range) (Doesn't hurt players very much?)
Defenders have an oppurtunity here to form up and counterattack, where they try to take out the slow enemy artillery bots/deployables.).
Breach
Destroying the enemy gate/s or Wall (High HP/High cost structure (Based on rank), can't place near each other etc)
Using a Short, one way teleport to breach a portion of the enemy defenses and gain access to some interior of the base. (High Volume [100U?]Long chargeup based on distance?, no cooldown but limit on number of players 5/10/20 etc, short range, maybe have another deployable on the other side to set up 2 way travel.)(Think of this as putting a ladder on an enemy keeps walls or tunneling under them or something)
Assault
Attack enemy structures, destroy or put into reinforced mode, kill resistance, or be killed, defenders have advantage of being able to redeploy quickly.
Other Thoughts
Limit Terraforming, but not to the degree it currently is (Maybe a height limit between tiles) need to be able to flatten out areas of land for use, and build roads with highways.
Encourage use of walls (New walls as an actual structure with gate/turret intergration?) painted zone might work to stop teleport walling, and discourage use of terraformed walls (Increase Breach time when near a wall?
Some way to make verticle walls or slanted built ones, not high ones, but extreme stretching of cliff textures is ugly.
No degredation on concrete tiles within "Claimed Area", maybe extend this to deployable walls, still can take damage though.
Basically, i want the player to be able to build a castle if they want, but i don't want it to be invincible from a well organised force.