I only did Platinum toward the very end of my session, so while I spent a lot of time on the floor, I was levelled up and had quite a few health packs by then, so managed to actually get some kills
The other 3 guys were amazing though. In all honesty I learned a lot from watching the others when I'd been knocked out in a round. It's well worth playing the harder challenges just to get the occasional insight into the tactics of better players.
What build is your engineer? I'm assuming you're using the human variant? Human engineers can chain tech explosions and fire explosions indefinitely if you have a high enough cooldown speed so the damage is insane.
You can easily top the scoreboard with an engineer, even with bad weapons as most of their damage comes from tech damage and explosions. Some people spec completely out of the combat drone but I take damage and shield increase in every evolution and take rockets at the end. Some use it as more of a distraction but its pretty unreliable, so I just use it for the extra damage and the potential to stagger boss units.
With overload you should take the chain evolution on level 4, on level 5 take recharge speed (it may seem like a good idea to take the knockdown instead but it messes up other peoples aim and makes it harder to get headshots and only weak enemies can get knocked over anyway). At level 6 you should take the shield damage increase. Overload has a 3 times damage modifier against shields, taking the shield damage evolution takes it up to 6 times damage vs shields.
For incinerate you should take radius(because of the way overload works, if you manage to get incinerate to connect on 2 enemies and you use overload afterwards, when the overload spark jumps to the second enemy it will cause 2 fire explosions at once, few skills have the ability to do that). Take the dot effect at level 5 to cause extra damage and stop shields regenerating. At level 6 take armor damage, the chilled bonus is nice if you have a lot of cryo ammo, but other than that its situational.
For the passive tree take power damage and weight capacity at level 4, at level 5 since you probably dont have any decent weapons, take power damage again. You may prefer to take shields up to 4 fitness tree and go without the power damage bonus in the passive tree, or just ditch the drone completely and go up to 6 in fitness for the extra shields.
You should basically just aim to chain explosions one after the other with the engineer. If the enemy starts off with shields open with overload, then hit it with incinerate afterwards, which will cause a tech explosion, then if its still alive, hit it with overload again which will cause a fire explosion(only works if the shields are down). Keep repeating until its dead
. Its generally better to open with overload as it cant be dodged and it will more reliably stagger 2 enemies.
There are a few enemies that are immune to powers, such as banshees when they're not in their warping phase(its still useful to use powers if you want them to stop throwing warp balls), praetorians when they're floating and phantoms when they're out of cover and not staggered. Other than that everything else is fair game. The only units you might have real problems with are phantoms are they're quite aggressive, their palm cannon really hurts and you won't have any reliable way to stagger them unless you have a weapon that staggers.
You should generally aim to keep the cooldown bonus as close to 200% as possible, so only equip one weapon that can be used in any situation. Tech/fire explosion damage is based off of the level of the skills that caused it and not passive damage bonuses, so going up to level 6 in both incinerate and overload will cause your explosions to do more damage.
You can play however you want at the end of the day but this is an optimal build.
