Magic: The Gathering - Duels of the Planeswalkers
21 Achievements
125-153h
Madness Suppressed
Defeat Sarkhan the Mad in the single-player campaign (Expansion 3)
5.8%
How to unlock the Madness Suppressed achievement in Magic: The Gathering - Duels of the Planeswalkers - Definitive Guide
He uses a Black/Red deck that is not as good as some of the decks that you have if you own the other expansion packs. See below for an option if you don`t have the other packs.
Fast decks that can kill creatures are the ones that are effective against him. I beat him miserably using the Relics of Doom deck and the Ears of the Elves deck was also effective. Other decks you may try are the Eyes of Shadow (use Terror to kill his Red creatures and Mind Rot to keep his hand empty) and Heat of Battle (just burn everything he summons).
A less effective option is the Thoughts of Wind deck if you manage to have counters for the big creatures he summons.
Sarkhan's final deck is is built around his Eldrazi (huge endgame creatures) and dragons using Solemn Simulacrum to accelerate his land drops and several removal spells to hold off until he has the required mana to play these massive creatures. Another card to look out for and which must be dealt with before its effect kicks in is Dragonmaster Outcast. The best counter would be a quick kill deck with several flying creatures and removal spells so the Relics of Doom deck would be the ideal choice, but again use whatever deck you feel comfortable using. You can also reduce the difficulty to easy if needed and don't be afraid to mulligan or reset to get a good opening hand. Once you defeat Sarkhan's final deck, you'll unlock the achievement and Sorin Markov's vampire deck, Master of Shadows.