Edward_R_Murrow: Every single one of your examples is wrong from the perspective of #1: high level BG2 play combined with #2: we're not interested in what is "theoretically useful" (since we could make that argument with all PoE spells as well and then the point is moot). Remember: we are
purely discussing high level relevance of low level spells here, since that's the only point where I originally disputed Felipepe. I have made no claims about mid-level play. So let's go through this one by one:
it [Mirror Image] still retains a good deal of usefulness as a combat protection that negates hits. While casters in SCS2 have numerous countermeasures against Mirror Image, many encounters don't have casters, allowing it time to shine. Things like golems, umber hulks, giants, some fiends, illithids, vampires, high-level fighters, elementals, and whatnot all have to go through the protection the "hard" way.
High level BG2 play. I cannot imagine any party that would gain
anything from casting mirror image against those opponents. They are literally non-issues. They're just bags of HP vs. your hasted blenders.
And even against enemies that have countermeasures, it can be an effective tool in baiting the aforementioned measures out or otherwise manipulating the AI. If my Fighter/Mage casts Mirror Image to ward against attacks but an enemy mage casts True Sight, Oracle, Remove Magic, or whatnot it's still a favorable trade. My character has expended a lower level spell slot than the one the enemy caster used and the enemy spellslinger was occupied for a round, not being able to attack/debilitate the party.
Purely theoretical point. In reality, enemy contigencies pop and your Mirror Image is dispelled. Not a single mage-fight in high level BG2 gains any benefit from you casting Mirror Image. Resources are not an issue in 99% of these fights.
Obviously this spell has a far higher utility to parties with Fighter/Mages
Not really. Fighter/Mages gain just as little from having their spell instantly dispelled by a stored true seeing/remove magic/motherfucking anything as any other mages.
-Melf's Acid Arrow still serves to effectively disrupt any caster it can hit.
Too bad it literally can't hit
a single mage in high level BG2 play. Literally not a one, even in Vanilla. Unless you stripped their protections, in which case they're dead no matter the strategy.
-As previously mentioned, Skull Trap was extremely good at dealing out lots of magical damage.
It seems you didn't read my posts. Skull Trap is arguably a bug. If you don't concede a 3rd level spell breaking the rules that all other (even HLA spells) follow a bug, then I concede that a 3rd level spell being one of the most damaging in the game certainly is useful.
-Sunfire is also excellent as it
Which enemy - pray tell - do you use sunfire against? Non-casters that are literally non-issues at the levels we're debating? Your fifth level spell slots are dedicated to the only once-in-a-blue-moon relevant spells in high level play - chiefly Lower Resistance and Breach. The first is used in combination with Time Stop and Alacrity to unleash the lower-level spell-flurries I discussed in the first post against largely weapon-immune but non-spell protected enemies.
Web, Glitterdust, Slow, Emotion, and Chaos can all stay relevant into Throne of Bhaal. While they'll be of little help against some of the highest-tier foes, replete with hard-coded immunities or lattices of spell protection, almost everything else is fair game to one or more of these powerful debilitations.
The reason this is wrong is that:
#1: Like you say, highest-tier foes simply ignore them.
#2: No-high-tier foes get destroyed without any other resource-expenditure on your side with the simple use of haste.
To illustrate, imagine a group in which six foes are vulnerable to one of these spells and within the spell's area of effect. Even if the foes all have "boss-like" saving throws (low single digits, in this case a Save vs Spells of 4), a quick binomial probability calculation says there's only around a probability of .26 that the player reaps zero value from the spell, that no enemies are effected. More realistic saves (Save vs Spells of 8) results in a probability of less than .05 of no creature being effected from the spells. Considering that some spells carry innate saving throw penalties, that some have longer durations forcing multiple saves, or that many spells will often effect more than six creatures, these spells can still greatly effect a battlefield.
In no practical ToB fight is it optimal to spend valuable miliseconds using your mage to cast fucking Emotion on low-level mobs when he could be activating his sequencers, casting HLAs and taking down protection/casting Abi-Dalzim.
And then there are some low-level spells that are outright all-stars, like Spook, Haste, Melf's Minute Meteors, Stoneskin, Fire Shield, and Teleport Field.
Haste and Stoneskin I already mentioned as exceptions. Minute Meteors are outclassed point-for-point by Energy Blades.
Again, I have to hold you to the point I am making and the discussion we are having. Felipepepe said that in Poe, unlike in BG2, spells were outclassed by greater versions of themselves. My argument was never that BG2 low level spells were useless in theory, but that their practical application wasn't that different from PoE.
Anyway, Fire Shield is literally useless unless you're on SCS that changes the spell to protect against insect swarm. Teleport Field is chiefly useful for the AI because it's sort of a cheat-defense vs. your fighters. Against enemy fighters it is much less applicable since there are almost no fights (portal fight in Warden's Keep comes to mind as the only one) that has actually threatening melee fighters. And here, unless you're on mods, they will attack in manageable chunks.
Again, your points are
purely theoretical. You
could do all the things you say,
just like you can in PoE. The question is whether it is surperior to just using your high level arsenal, and it is not.
I disagree with the assertion that low level spells become useless in the lategame of BG2, even with SCS2.
Your arguments only hold up as theoretical points, and those points can be made just as well for PoE. In fact they can be made stronger for PoE due to Sawyer actually implementing changes in the way spells are available on higher levels.
In a D&D-like system, there's a bit of a decision. The Dispel Magic might be necessary in a later encounter, forcing the player to think ahead and make a more interesting choice.
And there it is. I thought someone would make the conservation of resources argument at some point. Come on, Edward. Of all theoretical arguments you've made, this is the most theoretical of all. Unless you willfully enforce resting-rules on yourself, there is not a single fight in neither BG2 nor ToB that I can't start with a full arsenal at the click of a button.
And before you get started: no, arguments like "but what if you have a party of six mages" aren't applicable. I could make the exact same arguments in a PoE context.
TL;DR: Whatever "true" arguments you make fail to ackknowledge that we're only having this discussion because I disputed
felipepepe 's point that BG2 spells were useful into the late game to a much larger extend than PoE spells. Each time you say "well, theoretically, you could cast slow/melf's acid arrow here instead of something better", my answer is "sure... you can do that in PoE to, making the point entirely moot." The bottom line is that despite BG2's scalings, in 99% of all cases it was not correct to cast low level spells.
There is actually a defense for low level spells that you guys haven't made though. Spell Trigger, Spell Sequencer, Contigency and other versions of this spell arguably did more for low level spells than the low level spells do for themselves. Without the spell storage spells, low level spells would be used almost not at all. However due to these spells, you actually see the effects of low level spells even if you don't cast them.
to Edward_R_Murrow for demonstrating the diverse utility of low level spells in BG2/ToB. 
