you're right, very high intellect with blackhole spell is actually a boring combo. Don't know why they have done it like that, I mean, press a button and every enemy stack gets a damage. With deathstar you have actually use your brain. It is about self-imposed challenges I guess, just do not normally use overpowered spells, combos (droids, black knights etc), although I really enjoyed 100%crit shooters gameplay for example.
anyway, I managed to finish that 100% spell damage only playthrough
, screenshots attached as always. Over next few days I sit down and write some simple guide.