Summoning Magic

I am writing 2nd level spells tonight. I think I have come up with a cool summoning system.

First, there is an Abjuration spell called Containment. This spell is used to create and maintain a containment zone that keeps a summoned creature within a specific area. The classic pentagram.

You can summon creatures using either Conjuration spells (elementals, monsters, animals, etc) or Necromancy spells (spirits, undead, demons, devils, etc). You must then make a roll on the standard encounter disposition table to determine if it is friendly to you or not.

If friendly, you can negotiate with them to serve you. They do not serve for free. However, they are much more powerful than standard summoned monsters in most games. So if they serve you, you will have a really good servant to help you. Then again, if unfriendly..... this could get bad really quick.

If summoned inside of a containment zone, the creature cannot attack you and thus even a bad roll is not disasterous.... immediately. You must recast the spell every few hours and the creature will be gunning for you when it gets free. Since spells cost HP and it regenerates slower than you need, eventually you will run out of HP and the creature will get free.

At 3rd level, I am going to have a spell that will banish them from within the containment zone. At 4th level, a spell to banish them outside of a containment zone. And of course, more powerful stuff as you go up in levels.

Thoughts?

I am thinking this will create powerful temptation for 2nd level conjurers and necromancers to play with fire....