Quick summary of Finitevus from the wiki since I know a lot of people also don't know who this is:

Finitevus was warped into a cruel and twisted figure, serving a megalomaniacal desire to "rebirth" all of Mobius in a wave of emerald fire. Finitevus regularly remans cold and calculated in his speech, even during battle, although he is also prone to sudden and violent outbursts when his plans suffer large setback.

You can come up with what you think he would sound like!