So making some randomness actions also make the boss fight not boring?..
Custom Save/Load System only works for Multiplayers for me. In SRPG, you are the only one playing so it is very much fine just to use the standard's Warcraft Save/Load System. But it still depends if you want to use one.
What ever PurgeandFire said.
Also, add some "phases" to the boss. For example, some kind of dragon boss. First hes flying and hard to reach, but once you damage him enough he loses his wings and drops on the ground, making him easier to fight.
Or maybe you could add some quests/achievements to the boss fight. "Kill the boss in less than 30 seconds". People always like to try to get all the achievements. Atleast i do