I think everyone who has ever played a Spell Caster where the majority of their contribution be it DPS or Crowd Control or even Buffs have found themselves looking at an empty Blue Bar and asking themselves the Question - Do I drink a mnemonic potion or do I wait for the shrine?
This can be a tough question at the time it happens and made even worse when your potions will grant 300 - 600 SP back and you only need about 200ish. But have you ever stopped to ask the question "How did I get here?" and "What I could have done differently to get more out of what I have?"
Now back in the early days a caster with buff spells would "burn" any remaining spell points buffing party members that were not resting or rest last to buff others before they rested. While this wasn't a time saver it did help to conserve that SP for other uses. This method does still work as long as others are not in a hurry to finish the quest while you get your SP back so you can continue to contribute
But that is not really what I want to discuss. I want to discuss how Metamagic Feats can contribute to diminishing our available Spell Points, some of which we don't even realize (Like a slow leaking toilet)
The Big Boom Feats Maximize/Empower/Empower Healing
This is the need for big number when we cast a spell it is only second by the flashness of the spell - Be honest you like Fireball because of the explosion hehehe. But have you ever thought about the cost of that +25 SP when Maximized, or +15 SP when Empowered etc. ?
One of the features that the Monster Manual offers is the ability to know how many HP certain unlock monsters have as well as have left. But even before that a person that took time to observe a spell hit and its amount vs the movement of the Red Bar could make an estimate ie, 300 Damage moved the bar about 10%, hmmm this looks like it might have about 3,000 HP etc.
So what is my point? My point is we have options that allow us to scale how much SP we invest by adding the spell multiple times to the hotbar and setting the Meta's. Picking the right version of the spell can maximize the SP to Damage needed ratio. Allowing you to save between 15 and 40 Spell Points because the spell's base damage is enough to finish the job.
This was something I learned while playing a cleric with healing - Learning the right spells to use so that I could heal a person in the fewest casts but at the same time minimize over-healing. I've run with builds that were worse then WF with zero healing amp/or making heal friendly to players were a cure light wounds would be enough (and sometimes too much) to heal them. Again the trick here is learning when you don't need to spend the extra SP to get the desired result - Killing the mob.
Enlarge
Enlarge is by far one of the more obvious Meta's but it can cause problems with SP consumption if you leave it on. This is one I totally recommend having as its own Hotbar as the toggle off/on may be hard to remember/do depending on what is happening
Quicken
I have talked to several caster players that toggle this on and forget it accepting the +10 SP for a no failed concentration check. This is important because if you are tripped, made helpless or incapacitated while casting the Quicken will not prevent the spell failure.
But this is not a very Spell Point conservation way to use this ability. Sure it sucks to attempt to cast and fail - even more so if the spell was for healing and you died or was all that was needed to end that mobs life but now you died...
This is another Meta that is best used with a Hotbar for a specific purpose. The reason is that depending on your playstyle this meta only benefits you when you need to make a concentration check. If you spend more time outside of things like taking damage say as a back line spell chucker then you will have fewer instances of this feature. If however, you like to jump in the middle and blast away like a barbarian spamming cleaves then sure having this on all the time will be beneficial and you might want a hotbar where this is off so you can conserve for those times you find yourself outside of taking lots of damage - say when a tank/CC has the room covered.
Heighten Spell
I think of all the feats this one is by far the one that is nefarious. The reason I say this is we are constantly concerned about keeping our DCs relevant with some people looking for between 80% and 100% effectiveness in the content they are playing. Which is made even more so by the fact so many run elite and at level. But have you ever considered the cost between 5 SP (+1 DC) and 40 SP (+8 DC) vs what DC is actually needed to be as effective as your considered effectiveness. I'm willing to bet many turn this feat on as soon as they get it and never turn it off - I know I've done this until I really thought about it.
Example: This last life I ran on my Wizard I took Heighten, but decided I would not turn it on until I noticed stuff was saving. Now keeping in mind that at every level possible I always have the right Int booster - Including Insight and Exceptional from Greensteel and even a level 16 +8 Int item, so before anyone jumps at this, yes I realize Gear can make a difference [I have spell school gear appropriate for the level as well]. But is surprised me that it was not until I started to run the new content of "Search and Rescue" (I out leveled the other ones before I could give them a try) and only in the Drow area that I found I needed to turn Heighten on. Even then it was more to bring some of my spell DCs up but was still not needed for all my spells. I even ran the Amrath Level 13 quests in a full group without need to use heighten and my webs were very sticky.
Now obviously this does not effect your highest spell level, but consider what spells you are using and the potential of how much SP you could have had for another cast(s) if you realized your DCs were high enough with your natural abilities and available gear.
In the past I've talked about turning off heighten to conserve SP when you know the mobs are saving and taking 1/2 damage anyway. But people should also consider turning this off if your DCs are already high enough to be very to extremely effective.
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So if anything I hope I have stimulated your brain on thinking how you might be over-using SP when you don't need to.