Vavel's Volcanic mode has the ability will allow you twice as much power in the normal mode. This can be very helpful if you are losing a fight. If you are not very skilled at controlling Vavel yet, you should only use it as a last resort. If you start off in volcanic mode and cannot control Vavel well enough, you may run out of time and lose the fight. This is also the same with Vavel's Genesis mode, only you gain about four times normal power.