A follow up to Can you use Quickened Spell to cast cantrips? (and asked in the spirit of this question and this question), a L18 Sorcerer/L2 Warlock has 18 Sorcery points, and "recovers" 2 (so to speak) at every short rest (due to Warlock slots). This means that, for 9 rounds, this character can pump out 8d10+8d6+40 force damage vs AC every turn (including Hex), and push the target up to 80 feet (with Repelling Blast; a minor point, but worth mentioning). And they've yet to use any of their spell slots: if the character converted all their slots to SP, they could do this for 35 more rounds (unless my math is off, L18 Sorcerer/L2 Warlock = 70 SP in slots) + 1/round per short rest (due to Warlock slots).
So, a few thoughts:
- Given that AC is the most reliable defence to target, and force damage is rarely resisted, this is extremely dependable—there are very few (if any) encounters where this strategy isn't viable.
- The damage is better (more DPT) than casting Disintegrate 9 times in a fight—all while "using" only nine L2-worth of slots. In fact, it's better to convert an L6 slot to SP (instead of casting Disintegrate, for example), and pull this off over three turns—you'd get 12d10+12d6+60 extra damage vs AC, compared to Disintegrate's 10d6+40 vs Dex. And I'm not even subtracting the opportunity cost of the EB that wasn't cast. Comparing the use of 6 SP over 3 turns (2 EB per turn over 3 turns, vs 1 Disintegrate + 2 EB also over 3 turns; click the Summary tab for easier comparison), you get about 336 vs 187 average dmg.
- At the end of the fight, the PC can convert several low-level slots to recover a bunch of SP, ready to repeat this in the next one.
- And, the main thought: this breaks the attack economy, given that the weapon-attack equivalent (Haste), has a built-in restriction that prevents precisely this outcome (the extra Action granted can only be used for a single weapon attack). So, a Fighter would get, at most, an extra 1d12 + 5 + 3 plus... nothing that comes close to 4d10+4d6+20.
In short, unless I'm missing something, this is way more single target damage than any other class/ability combination, from up to 120 feet away (in an open space, you could even stay away of 99% of threats—and push them back 80 feet if they try to close in!), and way more damage than any single-target spell. Which means that, unless you're fighting multiple targets (and absolutely need some CC/AoE, or need to escape), there's no better use of SP, spell slots, or (bonus) Actions: spamming EB + Quickened EB is simply the best strategy to ensure victory asap.
So, what's the impact of a house rule denying more than one Quickened Eldritch Blast ray? Please refer only to your personal experience (or some suitably-backed analysis, according to good subjective criteria), and whether either scenario would break something I'm not seeing.