I dunno the over all goal of your project, But i do know that it's Blizzard, Blizzara, Blizzaga, Thunder (which makes no sense since thunder is the sound and lightening is what is actually shown..) Thundera, Thundega (could be thundara/thundaga, I just don't recall) if if you're going for cannon.
If you're trying to make sense out of spells that make zero sense, then you'd want bolt bolra and bolga, as they always omit the last letter it seems in spells. Just my two cents.