Mortars are currently pretty problematic. They are just miles stronger than anything else, and since the enemies don't seem to get the upgrades. You end up being able to fire 3x volleys of mortars before their first volley hits your backline. Which means their Mortars usually only get to fire once, then it's GG. The other units basically only exist to act as cannon fodder (or mortar fodder to be more precise). The actual win con is just "who has more mortars" and since we get to keep spawning them, that's always going to be us. But even if the enemy was spawning them too, the difference in attack speed would still automatically make it us.