Terratron boss idea.

The terratron is bound to be a good idea for a fight.  But i have one idea that might be a bit interesting.  First form is that in his natural form, all assembled.  Some of his attacks require him to move off the platform and lower altitude.  The attacks that do so will mainly be his blaster type abilities, like where his saw blase becomes a machine gun.

His blaster types will have the ghost academy either fire lasers, or a nuclear missile.  You'll be able to tell if the terratron is going to use the laser or not by depending on how the attack will start. if he goes into it without pausing, then he'll use what he used for the previous blaster attack, which is by default, laser and Concussion grenades.

the laser functions like the one the battlecruiser uses, but doesn't whirl around and follows the path of the ghost academy's trajectory.  Concussion grenades deal some damage, but are meant to slow you down for the laser attack.  If he pauses suddenly for a second before firing the blaster starport and the ghost academy, that means he's swapping weapons, to nukes and ion bolts.

The nuke will only be shot once, and will deal heavy damage and heavy range, but moves slowly and can be easily dodged, but a few mag mines are launched, along with one seeker missile.  the seeker missile functions exactly like the one in game. just outrun it, and you should be safe.

His Ion bolts deal heavier damage than concussion grenades, but don't slow.  He also has a sweep attack, he'll get close to one side while facing it, and sweeps, flinging his saw off in another direction. be careful for it's return trip.

The terratron also has a laser beam attack. you can tell he is going to use it if he dips lower than usual. he'll start off at one end and almost sweep his way to the other side.  He'll also drop off reapers to deal with you, which he does by opening up that factory.  

It also has a few other attacks. one is that he'll deploy the saw mid air, then graviton beam it so that it drops to the ground.  Also, he may deploy a missile spinner, which will shoot some missiles at a player, or act as a orbital laser beam, but occasionally drops down to have a swipe at a player. you can tell be depending on where they go after they have been released.

it also orders in a mule every minute after being at 1/4th HP, which repairs the terratron.  At half hp, the strategy changes radically. now he separates his own parts after flying high into the air.  The boss is now in multiple parts, and the planetary fortress is destroyed last, because it's invulnerable.  Each and every part has a role to play.

Planetary fortress: fires it's twin cannons, firing two concussion grenades at a spot and makes scv's to repair.  

once every other part is destroyed, this part gains flight, and can summon mules, scan parts of the battlefield, making players that are hit by it take extra damage, and after enough damage, calling down some supply depots so that it can become invulnerable.  Destroy this, and you win the fight.

Refinery: a few are instantly deployed.  occasionally fires a baneling, but nothing else is needed.

Supply depot: occasionally lowers and then raises to fling a probe in the fight, which will attack you.

Barracks: two are spawned instead of the regular one. occasionally makes a marine, reaper, or 2 scvs.

Engineering Bay: will fly into the air and occasionally create a missile turret or a sensor tower.

Bunker: four are spawned instead of one. will occasionally deploy 2 reapers or 2 marines and 2 scvs.

Missile turret: fires a few missiles at a target player before self destructing.

Sensor tower: fires a high powered shock at a medkit or a player with high amount of medkits. destroys a medkit immediately at whatever it hits, targeting the closest. then self destructs.

Ghost academy: fires a nuclear missile into the air, which lands down at some location, healing heavy damage with a large range.

Factory: deploys hellbats, widow mines(which burrow, attack player, then unburrow), and vikings in thier ground state.

Armory: increases armor of one structure by 3.

Starport: deploys medivacs(deploys marine then runs off), banshees, and when destroyed, releases a raven, which can deploy auto turrets, cloaking drones, grenades, and seeker missiles.

Fusion reactor: two of these are deployed instead of one.  occasionally fires a yamato blast.

That is what i have for the terratron boss.

For tier 4 bosses, I think this is a good idea.