ToME Wiki
General Info
Partial summons have two effects on your mana: reducing your rate of mana regeneration, and draining mana. The "Upkeep: X% mana" shown in the "Current Pets" display is actually the percentage by which your ordinary mana regeneration has been reduced, and does *NOT* include the mana drain; "100% mana" means you're not regenerating mana at all.
The mana regeneration reduction goes as follows: you area allow a certain number of partial summons without any reduction in regeneration rate at all. This number is 1, plus 1 more for every 20 player levels, or 1 more every 15 player levels if you have the Perfect Casting ability (making the absolute maximum 4, gained at player level 45 with Perfect Casting). If you exceed that number, then your mana regeneration rate is reduced by the sum of the monster levels of all your partial summons, in percent, maxed out at a 100% reduction, and with a minimum of a 10% reduction.
The main drain goes as follows: the mana cost per turn of each partial summon is:
((monster_level / skill_level) - 1) / 4
where skill level is scaled to 100. However, there is a minimum (floor) cost:
(monster_level * 0.0192) + 0.04
If your current mana becomes less than the per-turn drain rate, then you will lose partial summons until this is no longer the case.
Strategic Recommendations
Anyone who wants a (disorganized but very thorough overall) analysis of the ins and outs of playing a Summoner probably wants to read through the DayInTheLifeArchive/LearningCompetition/LearningcompAugust2005 entries and commentary.
Code-Related Information
ToME version 2.3.2 and earlier had some bugs related to the mana cost of partial-summoned pets. These are fixed in CVS (which should become 2.3.3 some day).
- The obvious one: partials who were out of your line of sight were not counted when determining upkeep.
The subtle one: upkeep was calculated every game turn for the monsters who happened to be processed on that turn, but you were only charged upkeep when the "world" was processed, which only occurs every 10th game turn. So you would only be charged upkeep for monsters whose movement happened to be occur on game turns ending with "0". GreyCat fixed this by accumulating the upkeep cost until the world got processed, instead of resetting it each game turn.
Chatter
PermanentInk: What factors go into how many partials, and of what type, I can maintain as a summoner? Specifically, does increasing my mana (skill points put into Magic) help, or not?
MayLith: Two things: Points in Summoning, and (for partial totems) points in mana. Pets summoned from partial totems cost mana to maintain, though that cost goes down as you put more points into Summoning.
Robed: Don't know if this is intended or not, but I've noticed that partials that spawn, like r's can grow to ridiculous amounts without the mana cost (or perhaps only the mana cost of the first; 0 if it was killed, but it's babies are still around).