The BEST stat in the game is Mblock. If you get it to, i think its 128 or more your character will be almost invincible. Every attack that is possible to block WILL be blocked, this includes magic. If you dont believe me then try this

Equip the Ragnarok Sword

Equip the Force Shield, Bards hat, force armor and Zephyr Cape (its a relic).

Then go into battle and try to hit that character with a physical attack or spells that CAN be blocked.