Ignite tiles that vek are emerging from and they will be on fire once they appear
Fire wont damage cities so you can freely target them with the Meteor Mech to push vek away from them, or shoot through cities with the Flame Mechs range upgrade to hit vek behind them
Fire does not damage cities, trains, or the bombs, but does damage other items with hit points you are supposed to protect (such as the earth mover, terraformer...)
Enemies that are on fire take fire damage before they perform an action, so the Flame Thrower and Vulcan Artillery can effectively do one immediate damage even without upgrades
Vek that aren't already burning won't deliberately stand in fire, so you can protect structures from melee Vek by igniting the tiles around the structures
Use the Swap Mech to drop land enemies into water/lava; or to pull guarding targets next to your freezing tanks.
Destroy the Dam missions are tricky until you power up the Vulcan artillery. It can't be set on fire, so none of your attacks can damage it. Look for opportunities to push Vek into the dam or redirect their attacks toward it.
If you have unlocked the Detritus Disposal island, try to save this island later in the run because the effects of A.C.I.D. when paired with the Flame Behemoths’ attacks can be devastating and prove very helpful when fighting later-game Vek.
Ignited Vek take damage from flamethrower instead of re-igniting.