Hehe, I've seen this happen before too.
Basically any existing spell, item, ability or alchemical item then work it pretty much exactly as is.
Beyond that, for a good high grade bomb - well, assuming the rogue has improved evasion I'd still say they're dead. Mostly due to the fact of the DC to avoid it being ON YOU would be so ridiculously high that I wouldn't even set it and just insist they fail. If they demanded a DC I'd say 50 or something beyond their ability to do then when they take HALF (for improved evasion) they still take massive amounts.
I actually did this where I blew up a town with a colossal+ fireball. I'm not positive of the exact size but the "pea" of the miniature was as big as a regular fireball (20-foot diameter). The rogue who lived with improved evasion got 100 damage. It was a campaign plot point, not a regular spell in case you were wondering.