Guidance
Reaction to a creature other than you making an attribute check
Range: 30 feet
Components: V S
You ask your divine patron to help an ally. As a reaction, you sacrifice a hit die, and the target gains a 1d4 bonus to the triggering attribute check, possibly turning a failure into a success. The target of the effect may choose to sacrifice a hit die to refund your lost hit die.
At higher levels: Starting at level 5, the target gains temporary HP equal to one roll of the sacrificed HD. Starting at level 11, the roll of the bonus die also increases the temporary HP, and at level 17 the roll of the bonus die becomes 1d6.
Resistance
Reaction to a creature other than you failing a saving throw
Range: 30 feet
Components: V S
You ask your divine patron to protect an ally. As a reaction, you sacrifice a hit die, and the target gains a 1d4 bonus to the triggering saving throw, possibly turning a failure into a success. The target of the effect may choose to sacrifice a hit die to refund your lost hit die.
At higher levels: Starting at level 5, no HD is sacrificed if the saving throw still fails. At level 11, the bonus roll becomes 1d6, and at level 17 1d8.
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How is that for less-spammed cantrips?
Well, for Resistance, it is going to be more used. But nobody used it in my experience.
The HD cost is intended to be modest. By making the Cleric commit their own HD, and then giving the target the option of saving the HD, the Cleric should be cautious about using it.
Both are "someone else". These Cantrips don't boost your own abilities.
For Guidance, I didn't want to break bounded accuracy. So I made it turn the lost HD into temporary HP (which keeps HP budget on-track), then granted a few extra HP and only then made the die larger at T4. If you spam it at one target these temporary HP don't stack, so it is less efficient. If you use it only sometimes, it acts as a little blessing from the divine patron.
Used modestly it shouldn't cause a HP deficit due to the temporary HP.
The Resistance doesn't get temporary HP for a few reasons. First, they are likely to be about to take damage; the temporary HP become healing. Instead I made the die grow larger. I find saving throws are more swingy than skill checks.
"You don't waste the HD if the check still fails" saves on "ok, how much did you miss by" time waste, so I put that upgrade early; it increases game throughput. For level 1-4 a bit of caution seems fine.
Resistance is triggered by failng the saving throw to make it clear that it isn't auto-wasted on a success. Attribute/skill checks often have a less obvious "pass/fail" number in my experience, so I avoided that mechanic.