Mech units have one great advantage. Get 1 stack of repair droids and 1 stack of guard droids. Split the Repair driods stack. Add something that can be resurrected by a paladin or an inquisitor and enjoy the no-loss victories. Since repair driods' ability is rechargeable, you can use it indefinitely on your tank (the guard droids) and on your repair droids (if you suffer any casualties) long after the battle is over and only a few enemy units remain.
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