Saruman, KoI is the keystone minion of most uruk decks in Fellowship Block, and, due to his immense power, is x-listed in all other formats, save open. KoI’s ability to make any and all uruks fierce is extremely powerful, as uruks will go from inflicting 2 wounds to 4 wounds a turn (Assuming they win their skirmishes). He can also absorb any 3 wounds that would otherwise be dealt to uruks, thus protecting against directed archery and allowing them to safely get through the archery phase. Furthermore, he helps uruks survive skirmish wounding and makes it very difficult to double move.

KoI has a natural synergy with Uruk Ravager, who is effectively cheaper with Saruman in play, allowing you to drop several uruks with Saruman at a site. Cheap uruks in general go well with this Saruman, as the stronger ones are too expensive and have more vitality anyway. You will then need many pumps and support cards to ensure these uruks can win skirmishes. Some examples are Savagery to Match their Numbers and Saruman's Ambition.
Be sure to only use KoI’s wound prevention to prevent uruks from dying (Unless they need vitality to exert) as many Fellowships have surprise wounding with PATHS and Bow of the Galadhrim, and it’s important you keep Saruman’s vitality available to deal with these surprise wounds when they arrive.
The best counters to KoI are Foul Creation and Betrayal of Isengard.

• Archery
• Hobbit decks

• Maneuver wounding