impossible gameplay tactics on XL.

Instead of sending heroes back and forth, you can try preparing 3-4 strong heroes: one with an army, and three with magic, and send them in different directions to capture all the neutral territories. And when you find a living opponent, you need to gather your forces into one and go to attack him. If he comes to you for the same purpose, then meet him :)
It is important to have FAST-MOVING heroes – whether it's due to logistics, artifacts, or spells; otherwise, by the time your hero reaches the enemy's borders, his heroes will have already ravaged your country from one end to the other.