Colossus is different than the other 3 javelins in that it doesn't have Energy Shields. It's just a big fat health bar. Health in Anthem is referred to as "Armor" btw. This means that while you can take more hits in a general sense, there are some caveats you need to be aware of:
Because of the fatter healthbar, Colossus tends to get more value out of health pickups. However, health doesn't naturally regenerate in-combat like energy shields. Because there's no energy shield, Colossus is more susceptible to elemental effects, such as burning or frozen(this sux donkey ballz btw)
Instead of an energy shield, the Colossus has an actual, physical shield like an old-timey knight. The shield is awesome. It's got its own health pool and regenerates after not taking a hit for a short while. While holding the shield up, it blocks attacks and elemental effects, but only from the front of the Colossus(180 degree arc, AFAIK). While holding the shield up, you can sprint through most non-large enemies, knocking them down and doing damage. You can melee with the shield too! There's even mods to increase melee damage with the shield.
The main drawback of the shield is that it only covers the front arc, and you can't use most weapons while it's up. If you fire your gun or activate one of your ordinance launchers, the shield comes down. There are a few exceptions. Both the lightning weapons on the back of the Colossus can be activated while the shield is up. You can revive other players while the shield is up, as well as carry most objective items.
What I've learned about playing Colossus is that you need to be super aware of your position. Alternate between getting to cover, picking up health boosts, and using your shield to get around dangerous situations. A good tactic is to light up enemies from range, killing enough to drop some health and ammo pickups, raise your shield, then sprint through to gather all the power-ups. Turn around, rinse and repeat. This isn't always a great idea, since if you run into a big enemy you'll stop and be staggered. Also, charging turrets backed up by elites isn't generally a good idea.
Managing your health and shield is going to be key to being a good colossus player.
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Hold up. FMA has Greed/Ling, who's entire fighting style is agility when he's not blocking with his diamond skin. Edward is all about agility too, since he can't really afford to take hits. He's constantly leaping around and dodging bigger opponents. Hell, even King Bradley is depicted as using speed and timing over strength. And the actual Ninjas(Lanfan and Fu) are both pretty damn similar in terms of fighting styles.
God dammit...now we're talking about anime. >_<