Summon Greater Demon
|Calls forth one of the greater demons of Pandemonium to serve the caster. With high power, the summoned demon will be less likely to be initially hostile — but the strongest demons may eventually turn against their summoner regardless.|
Summon Greater Demon is a level 7 Summonings spell which calls a single greater demon (i.e. tier 1 or 2) into existence. Note that spell power only affects the demon's chance to be hostile and its duration: there is a fixed 40% chance to summon a tier-1 demon and improved spell power does not make it more more likely.
This spell carries some inherent risks worth being aware of. The demons summoned may arrive hostile, in which case a few shots of Abjuration will come in handy. Even if they do arrive friendly, however, Tier 1 demons will only arrive charmed, with the duration of the charm set such that they will turn on you before they disappear (higher spellpower will extend this duration, as well as duration of the demon itself). Also, be aware that your demons will use hellfire (but not torment) without regard for your safety. In the end, however, having a Brimstone fiend or balrug on your side will greatly increase anyone's offensive capabilities. Tier 2 demons never turn hostile.
Try Haunt if you want a safer option of the same level.