(Need description)
Army Encounter
?
Free Peoples: If he encounters a Free People army he does considerable damge and can kill multiple characters. He encountered a Noldo army containing 3000 HC in 48 Armour and 100 LC with 40 Armour. The encounter left the army commander (but not all commanders in the army) dead. The army still lived with 518 HC and 21 LC. The estimated strength of Sauron is therefore 60000 due to the Constitution loss of the army. (Bobbins)
Neutral: ?
Dark Servants: Improves a random skill of all characters and might grant a Mage access to lost list spells. (Bobbins)
Sauron is a non-player-character that can only be encountered by armies. If he ends up in the same hex with a force belonging to the Free Peoples or a Neutral, he destroys the force and all attached characters. If he's encountered by a Dark Servant army, he'll grant a random skill add to various characters traveling with the army and might teach mages a lost list spell. Sauron's ranks are as follows: Command 100+, Agent 80-89, Emissary 100+, Mage 100+, and has a challenge rank of 143+ although it estimated to be greater than 300; he's never been defeated in challenge, to my knowledge (although it'd be interesting to see what would happen if a character carrying the One Ring personally challenged Sauron, or transferred it to him if Dark Servant).
(Jeremy Richman) My experience is that he increased whatever the highest characteristic is, and that he always grants a random spell.