IMHO, I just like Hellfire:D and with its effect on counterattack and the huge number of troops due to opening the gates, you can do a lot of good things..
But defense doesn't fit into my hero's development:D
In general, the optimal skill development for a demon looks like this:
1) Logistics and surprise attack
2) Luck: wide gates of hell and magic resistance
3) Dark magic: everything is useful:D
4) Attack: devilish strike + magic of speed
5) Defense: stone resilience + evasion or reflection
In general, I like the development described above:D
Добро и зло,
Есть сила и власть,
И много всего
Но знай ты одно,
Что все это чушь,
И лишь без любви
Не проживешь ты и дня..