Quote Originally Posted by nickl_2000 View Post
The 15% chance of missing is a little wonky and could serve to slow down the game some.

The bullet about HP instead of the spell slot is the most problematic. 1 HP for a cantrip is pointless since we aren't limited to the amount of cantrips we can use. Otherwise, you get WAY to many spells available to a warlock. With a good healing (especially one with Healing Spirit) you can drop spells at max level constantly and never think about it.
I am going to back both of these.

Again, I'm biased, but I despise flat miss chances. The D&D people got an unnecessarily nasty letter from me when a 3rd Edition wind walking party used the "80% invisible" with no qualifiers to sneak up on an ancient dragon in the middle of an open field. Unbreakable "XXX% something happens" mechanics have always rubbed me the wrong way. In 5th Edition, whether you are gaseous or incorporeal, you still take damage from magic weapons just fine. Force attacks routinely hit such targets, too. I don't see why this defense is more powerful than both.

And yes, the most dangerous thing about replacing spell slots with hit points is how easy it is to get hit points back. Since cure wounds is a 1d8 per spell level, it's a perpetual magic machine if the warlock multiclasses, since it's double the spell levels restored as used. And vampiric touch could be almost as bad.

Please reconsider. I hate to give advice...that's a lie, I love to give advice, but we're competing in the same contest. Might I suggest:
1) Replace the 15% miss chance with a Reaction, +3 AC vs a nonmagical attack.
2) When you cast a spell without a spell slot, you get XXX "ooze points" per spell level. If your "ooze points" equals your hit points, you are unconscious. If your "ooze points" exceeds your hit points, you're dying. "Ooze points" are cleared during a short rest.
or
2) When you cast a spell without a spell slot, your maximum hit points drop by XXX per spell level.

Cure wounds sets XXX to 4.5 on average.