Mastadooms are considerably powerful and dangerous, but do not normally attack wanderers unless provoked. If you spot one, give it lots of breathing room while you pass by.
Attack Pattern: Mastadoom mostly uses regular attacks, which involve smashing one character with its powerful trunk. It also occasionally uses blizzard, which causes fairly low damage to all party members, and the Bone Toss, which damages one member.
Basic Fighting Strategies: Mastadoom has quite a bit of stamina, it often takes three timed hits to beat one, and its attacks aren't too dangerous, so you should concentrate on weaker opponents in the enemy part first.
Advanced Strategies: Mario's Fire attacks are good if you want to take Mastadoom out quickly. Otherwise, rely on regular attacks. Terrorize seems to work well on them, but it's not a powerful attack in the best of situations.
To block Mastadoom's trunk attack, try to press A just after the trunk reaches its highest point, before it crashes down on the victim. It's also possible to block the Bone Toss by pressing A as the bone makes contact.
