War Metal FAQ/Guide

Attributes
Get stamina, stamina, and more stamina. You'll need 120 energy and put an equal amount into attack and defense. Each time you level, add at least 1 point to stamina and when you train with the Emperor, train stamina.

Alliance
Grow your alliance. Not only will a large alliance aide you in PVP, you need people to exchange gifts with.

Gifts
Combat units are useless. Do not send them and if someone send them to you, take the +5 Energy instead. Trade tokens for collections, stamina for epics and energy for advancing quicker and for getting those elusive bonus units that are unlocked when you finish all missions in an area. Components are for those interested in hosting epics.

Missions
Don't complete all 4 missions in an area, even though that unlocks the area bonus. Complete 3, go to the next area and get the better formation and commander.

Collections
Do swarms to get a better formation. As you complete sub-missions, see if there are any Attribute collections you can complete. Focus on getting Dune Runner, Isabelle, ExoDrone, SkyCom, Tiamat and the 3 below. SkyCom is more or less easy to put together because of the low token requirement and is essential in epics. If you're lucky, you'll get at least half of them when you complete the sub-missions in The Red Sands and Blackmarsh. Don't try to find the missing tokens in other areas. Even though the probability is higher, it's not high enough to warrant the the amount of energy you'll end up spending.

Epic battles
Scorpions and Dozer Tanks may look powerful, but they're useless in epics, and so are any units without a secondary attack. For structures, use SkyCom and missile silos. Until you get missile silos, use Thermite Bunkers and Command Center. For units, Dreads and Infiltrators until you can get Sabres and Hatchlings. Then Mech Walkers, Chimeras, Razors and the better units from Collections and Combat Rank rewards.
Do not break cap and when you host, don't forget to set a cap.
Hatchling swarms, especially those with 3.5k and below caps are a good way to get better units and tokens.
Wyrms are a lot easier than Chimeras so do a couple 105k ones for silos, and if you're lucky, 5 fangs for your own personal wyrm.

Hatchling Swarms

Once you collect enough Mech Walkers and are doing these just for the tokens, be nice. Unless the battle has too many ghosts, I tend to stop at 30% to allow lower players to get their Mechs.

I do, however, check back often to make sure cap has not been raised.

Chimeras

If the chimera is killed before 100 people join / the Rail Cannon is brought online, there will be no chimera drops. Once 40 hitters join, start asking for ghosts and be careful not to kill it accidentally before the event is maxed out.

Xeno Mothership (XMS)

Loot is damage based and there is no point in chasing cap breakers. The only thing chasers are doing is wasting stamina and taking away loot from lower players.

Here are 3 useful sites you can refer to for proc rates, location of tokens, general info and an epic battle damage and percentage calculator:
blem.org
War Metal Guide
Proc Rates