Its obvious .. .u have to use it hell a lot if u have just one unit to kill all those impossible stacks ...
U cant realy prevent geyser .. just resssurect with paladins after caster mana is out .. geyser is just nothing compared to fire rain or armageddon
Beating samman with 360 mana armegodfing and fireraining you on harder diffculites with no loss is rrealy a challenge ( on normal i kiled him in 4 round with power of mage spells but on har dor impossible it wont work)