To be exact, my flame dart hits for 198, while my shadowbolt hits for 96. Lowest I've seen my flame-dart for is 174.
Perhaps we can add an unresistable nuke that does 75% of the damage - basically, a more powerful shadowbolt. Perhaps a water nuke that does 75% of the damage plus slows the unit.
Or an earth nuke that does 75% and has a chance to root/immobilise the unit.
Basically, as per the info provided above, there is nothing better than casting flame-dart and horrific wail at the moment. Zero reason. Not Soulburn, not Shadowbolt (with 1 exception - things immune to fire), not drain-life - nothing else.
Some other element contenders would be nice.