I have been messin with Summoning since I mastered Conveyance and is the Hellgate supposed to only be level 10? It seems like I had used summoning some on a module a while back and I thought I got a hellgate that was much more powerful. Maybe not, that was a while ago.
Well since the hellgate has to be maintained you would constantly have to be using restore fatigue potions in order to keep it.
Yes having a higher constitution helps in regenerating fatigue - you regenerate as much fatigue/5 seconds as much at a rate determined by your constitution/4. Because having 20 constitution means you regenerate 10 fatigue/10 seconds you can easily pull of first spells like strength of earth and/or purity of water and/or agility of fire with actually INCREASING fatigue! (3 basic spells amount to 9 upkeep/second while having 20 constitution means you regenerate 10 fatigue/second). Note: This is not the case if you have a constitution of 3 - such a low consitution does not allow you to regenerate any fatigue which means even pulling of strength of earth you will still get the full upkeep in fatigue penalty (3/10 seconds), a continual fatigue drain of 1.5 fat/5 seconds. But what sort of mage (or even technologist) would care to have a consitution so low it doesn't even resist poison in the slightest?
What I meant by leveling up was that the higher your own level, the better the creature you could summon using hellgate. As such, keeping it summoned permanently might even be a waste of time, since you could summon a higher level creature. I've only played a summoner once so I may be wrong, but I thought the familiar stayed with you until it was killed and did not need any upkeep? As such, it levels up when you do.
It is very strange, because I played a summoner, but I think the best summon ends at guardian ogre. Cuz they were so much better than the hell gate or familier.