The 3 different blasts are a bit off.
- Ray is by far the best of the 3. High damage, attacks AC.
- Spasm needs to be more different than "wisdom save". Also, forcing one foe to make 4 saves from one action is, prior to this feature, a no-go in 5e.
- Scythe is just sad.
I'd drop Wisdom casting. Int/Cha. Also, you should tie
something else to that choice to make it more than a charop decision.
Warlocks get Int/Cha saves, having those be the spellcasting choices make sense. And Wisdom doesn't line up with the "pact with another being" fluff as well. Even a celestial warlock can be Int or Cha.
A 5th level baseline warlock can cast 2 level 3 spells.
Your warlock can cast 1 level 3 and 1 level 1.
A 9th level base warlock can cast 2 level 5 spells. Your warlock can do it at level 10.
Now that 9th level version of your warlock can cast a 2nd and 5 1st level spells, which is a buff.
A 11th level base warlock can cast 3 level 5 spells and a level 6 spell. Your warlock would need 21 spell points to do this (plus level 6 pseudo-slot).
Spell points also feel sterile to me. I am going to propose some retrained chaos.
Restrait: When you cast a spell using a Warlock spell slot, you can choose to cast it at a lower level. Roll 1d6 plus the number of levels you reduced the spell slot; if the result is 7 or higher, you retain the spell slot. If you fail to retain the spell slot, you gain an additional bonus to your next retain roll equal to the bonus on this roll (until you next take a long or short rest).
Ignoring the last sentence, if a level 5 spell is worth 7, then a level 4 costs 5/6 of it, a level 3 4/6, a level 2 3/6 and a level 1 2/6; the ability to carry over retain points makes the lower level spells a bit cheaper than this.
It reduces bookkeeping, and replaces it with a bit of uncontrolled chaos. It also means that such a warlock is no worse off than the baseline warlock spell wise.
They do need to keep track of their retain points. And there is a strategy to them; casting a 1st level spell at level 9 is +4 regain points. If you lose the spell, you are 100% guaranteed to be able to cast a level 3 spell (4+2=6) without consuming the slot.
It also opens things up to blood magic. Like, being able to self-damage to gain a bonus on, or reroll a retain roll, or even make a retain roll on a non-restrained spell slot.
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Agonizing blast remains ridiculously strong, available at level 2, and not taking it makes you much weaker in combat. It is a kind of trap option not to take it unless you are doing a MC build.