Unfortunately, the rise of the Mana Beast is not a solution but instead an even bigger threat, as the dragon is a creature of sheer strength with little to no control over its rage. If it were to appear, the clash of power between it and its opponent would cause considerable damage to the world, and if it were to survive, it could destroy anything that's left, country after country.
The Mana Beast has already risen at least once, when corrupted wielders of the power of Mana created the Mana Fortress, an immense floating castle-warship of unparalleled might. The Mana Beast was summoned in retaliation and it attacked the fortress, allowing the Goddess of Mana to seal it inside an island which sunk under the oceans. Then, the Goddess called back the beast and ended the threat.
In Secret of Mana, the game's main villain, Thanatos unleashes the monsters of the Underworld of Mavolia (the Mana counterpart of Hell), severly weakening the Mana energy that sustains the world. He later reactivates the Mana Fortress and uses it to destroy the Mana Tree.
As the rise of the Mana Fortress automaticaly triggered the appearance of the Mana Beast, with the Mana Tree destroyed, no one would be able to stop the dragon once its job is done. So when they defeat Thanatos, the heroes have no other choice than to fight and to slay the fearsome beast, whose demise cause every creature in the world to disappear, including Popoie the Sprite (one of the three protagonists).
When fought as a boss, the Mana Beast is not too hard to defeat, especially if your character's levels, weapons and magic are strong enough. But it is a very long battle as the Mana Beast has 9999 life-points. The dragon casts a Wall spell that lasts during the whole fight and sends back at you every attack spell you use. Have Randi (the main hero) wield the Sword of Mana and have Purim and Popoie cast their Mana magic on it.
When the Mana Beasts fights you at close range, pummel it without end with your strongest concentrated attacks. The Mana Beast retaliates with the Lucent Beam spell at level 8. You cannot dodge its attacks when it starts to fly and charge from behind you, from before you, from right to left and left to right; or worse, when it goes at the bottom of the screen and hurls a gigantic whirling fire blast. (Cast a healing spell at the very moment the fire blast reaches you. You can also protect your characters with a potent enough Lucid Barrier spell but you need to cast it whenever the Mana Beast launches its attack.) These attacks strike your three characters and the fire blast is purely devastating, so heal whenever it is necessary.
A much smaller version of the Mana Beast appears in the unofficial, hack computer game Super Kitiku Mario, also known as Brutal Mario, where it serves as the mount of Larry Koopa and where it does most-to-all of the fighting.The Mana Beast attacks by firing two, then three flames, then a huge energy ball, before flying out of the screen and hurling flaming bolts from above and restart from the beginning. The fight is pretty easy and Mario just needs to jump on Larry's head three times when he and his mount are onscreen, though Mario must be equipped with a Floating Cloak to reach his foe without falling from the tower and lose a life.
Another reference to the Mana Beast is made when Mario as to fight the green Lady Boo from Paper Mario. Here, Lady Boo is a boss who fights by hurling different kind of fireballs. The more hits she gets, the bigger and stronger she becomes and at some point of the battle, she goes to the bottom of the screen and start attacking with the Mana Beast's signature whirling fire blast. The only difference is that her fire blasts are smaller and can be dodged, but that she fires them in a very quick successsion, which can prove very bothersome.