Monsters with the mythic trait have access to a pool of Mythic Points and are particularly strong for creatures of their level. Many mythic monsters are either resistant or entirely immune to attacks from non-mythic creatures and weapons.
1/ So a party without non-mythic weapon can't fight the oozeshard ? And the party will lose the fight ?
3/ With 3 Mythic Points, how can the oozeshard use it ?