Inferno tactics.

I like to play with weak factions, and I often win, especially with Inferno. The tactic is as follows, but it works if the game is long and on XL+U difficulty.
Hero: Zidar (Magic)
Inferno units: Efreet, Devil, Cerberus
From Griffin Towers and various Hives: Angels, Wyverns

Try to find another faction within two weeks, build Archers there, and 6-7 high-level units, and strong damage dealers, even level 4-5.
Even the Sphere of Inhibition won't help here, and magic is needed to gather normal units and fight them... I often do this.