The best Leviathan abilities in FF16 ‘s Rising Tide DLC are Tsunami and Cross Swell. They work perfectly in tandem to control the battlefield, grouping your enemies together and wiping them out ...

Leviathan's weakness is lightning, so have Rydia cast Thundaga each round. Edge, until he runs out of MP (at which point he should physically attack), should cast Blitz, one of his Ninjitsu spells.