Custum CR help for spellcaster

[Brundle]

Hey guy's new to theese forum's, Well at least first post been lurking for a bit. Hoping I can get some help .

In my New campaign my player's might be trying to fight threw a town and I made a custom npc for the mayor's of each area to fit into my world , My problem is that i'm not sure how to figure his CR.

This is the npc , It was created for the npc to have access to spells it needed, was originally mostly modified from Priest(pg348 of monster manual)which is cr 2, however this version tho has MUCH less dmg potental , Im not really sure how to guage the sleep spell for Cr, or his ability to lead guard's to the party

Armor Class 10,13 mage armor Hit Points 29 Speed 30 ft.
STR 10 (+0) DEX 10 (+0) CON 12 (+1) INT 16 (+3) WIS 13 (+1) CHA 13 (+1)
Skills persuasion +5, arcana +4 history +3 Senses passive Perception 12
Spellcasting. is a 5th-level spellcaster. Its spellcasting ability is intel (spell save DC 13, +5 to hit with spell attacks). spells prepared:
• Cantrips (at will): light ,message, ray of frost
• 1st level (3 slots): Sleep. unseen servant, illusary script, mage armor
•2nd level (2 slots) Suggestion, locate object, darkvision
•3rd level (1 sot) Sending
Actions
Club. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: (1d4) bludgeoning damage.

My target cr was about 1, for dmg per round and stats this seems liek it should be maybe a 1/2?, Although it was modified form the cr 2

[Unoriginal]

If the main combat ability of the creature doesn't cause damage, use the save DC instead for the calculation.

[Brundle]

Thanks for the reply, going off the chart on 274 dmg this would fall under 1/8th?

prof +2, ac 13(with armor) 7-35 hp and dc 13, The 13 dc does scale up to cr 3 but that's also up to 101-115 hp

It doe's have the sleep spell, I wasnt sure if I should be counting that as its damage per round, As it might take 1-2 pcs out of combat.

I would normally just not pay attention to the cr at all , However it is looking like they will be encountering a number of this type of enemy so I'd like to be able to get the way to figure the cr down.

The avrg sleep for first 3 rounds is 40ish. Which I know isn't the same as damage that would be cr6, and halving it to 20 would be cr 2 ish.



Again thanks for the help, The non damage type spell's is just kinda confusing me on this