Supply Platforms can be upgraded to provide one of:
+3 range to all nearby units and structures (Including Healing Drones), as well as detection, and vision over a large area
A mediocre turret
Supply Platform upgrades cost 75 Hexite
Production buildings can slowly heal one nearby unit at a time
Harvesters have a decent Healing Wave ability that restores 150 health to units
Defense Tips
Predators are great when defending one accessible location or choke-point. If needed, call down Predator reinforcements, drop the mine, and reposition them
Missile Platforms are not very effective; at most, they can buy some time
On Frozen Watch and Hillside, Striders with Bastions work well all around
On Iron Shield, one Bastion reinforcement can handle most repeatable attack waves
On Extraction, Predators can camp the spawn points while a mobile Titan or air army crosses the map's many cliffs