Lead the charge with Rolling Thunder and slow enemies with Majestic Roar.
Volibear benefits a great deal from additional Health and cooldown reduction.
You must attack three times in rapid succession before Frenzy can be activated - having the toughness to survive for a long time is one way to accomplish this goal.
Volibear can gain great Movement Speed while chasing targets, but he gains much less of a bonus when running away.
Volibear regenerates a large amount of Health when he drops to critical Health.
Slowing or stunning Volibear when he tries to charge will greatly reduce his effectiveness.