Since its been a while from my last set of hero ideas, I decided to do another set. This will involve possible Sci-Fi heroes.
Hellbringer: A flamethrower troop.
Volatility - There is a 1% chance that the hellbringer will explode from an attack when his hp goes below 1/4th of it's maximum. When this happens, he deals massive AoE damage to everything within a 600 foot radius. Flamethower packs are known to be volatile when hit.
Ignite - As the target takes more hits, their skin starts to burn off and they start to feel the heat of the flames more and more. The target takes additional damage with every hit tacked on, and this lasts for atleast 30 seconds. You could also make this give them damage over time for that duration based on how many hits they took.
Flamespray - The hellbringer uses his flamethrower to cause massive damage to anything ahead of him in a cone formation. Swinging his flamethower back and forth a few times, he hits enemies up to 5 times for his regular damage. During this time he is unable to move.
Burninate - With his love of fire, the Hellbringer puts some extra power into his building destruction. He gains a new buildings only attack that launches a heavy flamebomb that deals massive initial damage and also puts the tower out of commission for a few moments. This is a slow but long range building only attack.
Incinerator: My second flame troop idea.
Flameburst - Every 20 seconds the attack of the incinerator becomes a massive wave of flame, dealing mediocore damage. This damage can light the enemy up if they are covered in kerosene.
Kerosene - Douses the enemy, making them light up if hit by flameburst. this also makes them move slightly slower and have a chance of missing, since kerosene can be slippery.
Cauterize - Deals minor initial damage, but restores hp over time afterwords. This won't kill the person, but it can bring them to around 1hp. The flamethrower can also cauterize himself, but when he does he takes less initial damage since he is used to the burn of a hot flame.
Flaming Debris - Launches a number of odd and strange items that explode on landing, dealing massive damage to things in an area of affect. Everything from a rock to a racoon is used to do this, but the vessel has no effect on just how burnt your enemy gets.
Demolisher: A rocket launcher equiped guy that has a love of explosives.
Secondary Fire - When switching to secondary fire mode, the demolisher deals heavy damage with a shot of 3 rockets at once. This means it takes him about twice as long to load, but he deals about 3 times as much damage. This can't go on for long though, because this takes a large toll on his gun.
Camera Missile - Fires a missile a long distance that sees all along its path to the target. It explodes when it lands, dealing minor damage.
Mini-Nuke - A small nuclear device that can do about as much damage as a single bomb. This is a massive AoE, but the initial damage is minimal. The real problem is the nuclear fallout that will infest an even wider area, weakening all non-mechanical units, friendly or enemy.
Call in the Bombers - Calls in a few bombers that carpet bomb in a line perpendicular to the direction you are facing. This is most effective versus fortified positions such as towers and bunkers, but still hurts troops to some degree. (Perpendicular means it would intersect your facing direction along the point, creating 4 perfect right angles. If you know math, then this should be easy to figure out without the explination, but some people just don't know what perpendicular is.)
Sniper: A new take on this often overused hero style.
Prepare - Unable to attack at all in his normal form, even with skills, the sniper needs to set up before he can attack. This increases his line of sight to 1500 during both day and night, and gives him a 1500 attack range. The attacks are slow, but insanely damaging. He is unable to move when in prepared mode.
Improved Aim - His attacks become increasingly more deadly, allowing him to hit in areas that will deal more damage to the target. This gives him a 20% chance to do a minor extra amount of damage, both which increase when the skill is leveled up. Also has a 3% chance to instantly kill a non-hero unit.
Uranium Tipped Ammo - This makes shots armor piercing. When activated, this skill will deal no additional damage, but will cut through enemy armor. The amount of energy needed to fire these shots off will decrease as the skill goes up.
Camoflague - When this skill is turned on, the sniper is permenantly invisible, but it reduces his energy at a quick rate. This skill can be activated while both prepared and unprepared. if he is hit by anything though, he is revealed. This does not include AoE attacks, but only if someone can see him and attacks him.
All I can think of for right now. Maybe you can turn these into something useful. | 
