How to defeat royal ludroth in monster hunter 3?

To defeat Royal Ludroth in Monster Hunter 3, focus on targeting its weak spots, particularly its head and the sack on its back. Use weapons that deal blunt damage to break the sack, which will significantly weaken it. Maintain mobility to avoid its water attacks and try to bring along items like potions and traps to aid in the fight. Lastly, consider using elemental weapons like those with ice damage to exploit its weaknesses.