Can be slightly improved upon without crashing the game, just with tweaks.
Dropping one Blood to Power or Crit on Bloody (I dropped the crit) and adding an extra Spells to Power at the end with the free slot let me hit 2.62e+22. I fired it once, swapped wands, then fired it twice in a row (for a total of 3 times) to double up on the projectiles absorbed. Could potentially build up more projectiles for more absorption gains but eh, I feel like that's not in the spirit of the fight.
Alternatively, the game just barely survives replacing the DB2 with a DB3. Firing it 3 times results in a crash, firing it twice does not. This method hit 3.69e+22.
I'm not sure that this method can be pushed much further with such tweaks unless some shenanigans can be done to get even more copies of Blood to Power and Crit on Bloody. Duplicating Spells to Power more is out of the question as it's too resource-intensive.