Focus is a special ability that targets all active party members, and raises Magic and resistance to magical damage. Its effects stack up to 5 times per party member, and remain until the end of battle.
Focus raises the Magic stat by 1 point per cast; this can even raise the Magic stat to 260 during battle. It also reduces magical damage in a manner similar to the Shell spell; after a magical attack's base damage has been calculated, Focus reduces that damage by a certain percentage. Casting Focus once cuts damage received by 1/15 (or about 6.67%). Each additional cast raises this damage reduction to 2/15, 3/15, 4/15, and finally 5/15.
Raise the user's Magic.
Concentration is a support ability learned at level 71 in Dissidia, and level 58 in Dissidia 012. It increases the character's Bravery by 10% of their level's base Bravery approximately every one and a half seconds if the character takes no action for five seconds. Mastering Concentration learns Concentration+, which grants +30% Bravery, then Concentration++, which grants +50%. Taking any action or being attacked ends Concentration's effect.