OMAHA, Neb. — A day after it gave up the most runs ever in a College World Series game, LSU cranked up its offense and won its first national title since 2009 with an 18-4 victory over Florida on Monday night in the third and deciding game of the finals. LSU (54-17) staved off elimination three times in bracket play and bounced back from the humiliating 24-4 loss in Game 2 to claim its seventh championship, second to Southern California’s 12. The Tigers wiped out an early 2-0 deficit with a six-run second inning against Jac Caglianone (7-4).