I'm still in my first playthrough, so am likely to be off base on some points - but from what I understand Source Points went from being "too available" in the previous patch (with Source pools, Source vampirism, and soul jars) to "too scarce" in the current patch with soul jars being the only ... source of Source.
Problem:
Source Points are a resource which are used for powerful abilities, quests, and gaining access to certain areas. Although we can only play a limited portion of the game at this time, it's probably safe to assume that this resource maintains its value throughout. What's not safe to assume is if they will be easier or harder to obtain later in the game (or between patches).
Since the same resource is used for quests/exploration and skills, it creates an awkward juxtaposition. If the resource is scarce, it makes it feel meaningful from a questing perspective because you have to pick and choose how you use it - but will also heavily dissuade you from using it for powerful abilities. If the resource is too common, you get to use these powerful abilities to easily clear fights without having to sacrifice potential quests/exploration.
Ideas:
1) Divide the resource:
Have a scarce resource used to fuel powerful skills and another used to fuel quests / exploration. This way both feel meaningful without having to completely exclude one or the other. The drawback would be breaking continuity of "Source as a resource used in various ways" - and taking out a layer of complexity in the choice of how to use it.
Related option - have a global (time based) cooldown on the powerful abilities instead. The drawbacks there would be - swapping out abilities on cooldown, or afk-ing the cooldown which, while lame, can decrease the achievement factor of some higher difficulties.
2) Strike a better balance between risk/reward:
Perhaps increase Source Point availability, but also increase the risk associated with acquiring "optional" Source Points. Something along the lines of "the risk associated with over using the Helm of Braccus Rex" but more of that. Maybe an option to attempt to draw a Source Point in combat, with the risk of summoning additional enemies or damaging your characters. Maybe reduce the combat effectiveness of source skills.
What are people's thoughts on the matter? Do you like the new system? Have any ideas for a better approach?
