Welcome to the forums!
Just a few pointers from the top of my head, you could:
- Stop/reduce the amount of military units produced by the winning side by smiting one or more required finished good producers in the respective town
- Summon mythological creatures for the loosing side to tip the balance
- Place mythological tokens to buff (human) units of the loosing side. Note that you can place tokens of the winning side and let them be picked up by the loosing side as well (this works wonders with e.g. Adamantine or Nemean Lion)
- Use god powers to destroy all units/military producers to reset the scales (given the respective gods, naturally)
- Protect towns of the loosing side by smiting tiles or placing lakes, mountains or similar
- Upgrade units of the loosing side using direct actions (given the respective resources)
- Use action points of the winning side to help the loosing side e.g. by placing protective terrain
- Simply stop building up the winning side for some time (even by wasting action points if necessary)
- Create bottlenecks by placing terrain or smiting tiles to prevent the winning side from being able to bring their advantage (e.g. in numbers) to full effect
- Given enough deaths have been accumulated by the loosing side 'Convert' an especially powerful unit of the winning side using the respective direct action
- And lots more