Reyvaroid (boss)

This is Gengai after he was transformed into the first Reyvaroid Slave unit upon falling in one of Raphael's traps, so you will have to fight him in order to release him from this horrible state.

The Reyvaroid itself isn't much different from any of the more advanced Doll Model Antibodies, as it has their same attack patterns, all of which are easily avoidable. However, it has to be noted he has a pretty decent resistance against physical attacks, half of the elements and is pretty resistant to Song Magic, so you would do better in using the Ultra Supermoves to damage it. However, be careful with the Antibodies accompanying it, as these pests can easily attack all characters surrounding them, so if you aren't careful, you will get surrounded by a group of attacks that you won't be able to avoid and end up killed. The Reyvaroid, like most bosses encountered so far, can cause all status ailments with his attacks and also has his own Stored Attack: the D-Wave Flare, which releases a potent pulse of D-Waves similar to the DFP that causes large physical damage to all party members, so make sure to keep your HP high in case you can't interrupt it.

For winning this battle, the best you can do would be first Purging your Reyvateil and allowing the Burst Gauge to reach a percentage between 30000 and 50000 to then use her Song Magic, which should be enough to wipe out all the Antibodies. Once you have done that, you can just surround the Reyvaroid with all your Vanguards and continue attacking however you want to finish up the battle. However, mind that the Antibodies will try calling for help with their Stored Attacks if you don't finish them off and aren't careful.