The only spell that notably is useless with banish is: + Firestorm + Chain Lightning from level 4 The spell above do NOT give increases in damage even after banish.
Now, the 1 spell that is completely useless with banish is: + Shadow Strike The spell literally will deal the enemy 0 damage as "shadow strike" is the ONLY spell in game that does PHYSICAL damage. Yes, it's like a dark trying to kill you when you are banished. Kinda impossible (and for this case, waste of mana)
Thus, thunderstorm will NOT cancel. It will HELP you only with the damage. 30% more dmg I believe. And usually, you keep banish at level 1 or 2 as the CD is similar BUT the mana costs painfully much. Also, the % is same whether banish is level 1 or 6. And if you are wondering how long banish lasts, go play a CHF and check the description in the spell arena in the first 20 sec of game, lol. I highly encourage if possible to keep banish at level 1 all game until level 16. It is simply not worth it to upgrade. After level 2, it just soaks up lots of mana -.-
in regular 5.4, using banish was super useful when getting attacked by darks as they were slowed down to shit. its a shame that level 6 banish, hex, and silence are so easily dispelled. http://chf.ucoz.com/forum/71-3499-61942-16-1396993348