I am Metatron of the Ten Wise Men, and fighting me will be the greatest achievement you'll ever have!
― Metatron introduces himself to Claude and party in Eluria Tower prior to engaging them in combat.
Metatron is a boss in Star Ocean: The Second Story and Second Evolution. He is one of the Ten Wise Men and is fought twice in the game: atop Eluria Tower, and the second time in Armlock, although he is undefeatable in the first time, and must be stalled for a certain time.
Strategy
Metatron is probably the hardest Wise Man up to this point, due solely to his Metashield, which renders him invincible while it's up, and lasts some seconds. Other than that, his behavior is similar to Zaphkiel's, where he chases the player and hits him\her hard with close-range sword combos.
The best strategy is to hit him with attacks and special skills, and hack at him while he's stunned. Upon taking hold of himself, he will probably raise his shield immediatly. An easy way to defeat him, is to use three melee fighters and a healer, setting their tactics to "Stay away from enemies" as soon as he raises the Metashield. As soon as his shield fades, immediatly attack him, swiftly changing the fighters' tactics to "Attack with all you got" and the healer's to "Focus on Healing". Watch out for your MP though, as late-game skills can drain it fast. You should have few problems with him with a party average of level 60-70 and equipment from North City and Armlock.