CR, and immunity needed

[limejuicepowder]

Borrowing the idea from someone else on this forum (sorry, I forgot where I saw it), I'd like to design an NPC party of 4 hexblades, each with a shocker lizard familiar.

Yeah it's obvious where this is going. They approach like a normal group of fighter-types, but they close to melee the lizards (riding in a backpack or something) start blasting away. I see nothing to prevent the lizards from doing a lethal shock on each of their turns, creating a 8d8 blast of electricity 4 times per round. The hexblades would of course debuff to the best of their considerable abilities, making the save not so laughable.

So, questions -

1) the hexblades need immunity to electricity.

2) assuming the hexblades are the minimal level needed to get a shocker lizard as a familiar (5th w/ practiced spellcaster), what's the estimate CR rating for such a group?

[awa]

by raw familiars are class features not separate creatures and thus do not add to the cr.

edit are you sure it's not 1 8d8 shock rather than 4. I found the text some what confusing but felt it leaned more towards the former

[limejuicepowder]

The familiars wouldn't change the CR in and of themselves; I was more referring to the overall synergy of the encounter. An encounter rating might be a better description.

So your interpretation of the lethal shock ability would use all of the actions of the shocker lizards for the entire round? Gets a lot weaker that way :(

[awa]

if it didn't work that way then there cr is really wrong with them having a fairly good chance of a one rnd tpk.

In the grand scheme of things 4 hex blades (5) has a cr of 9
a cryo hydra 8 heads is also cr 9 and can put out 24d6 damge

The trick is good but cr is a wonky thing honestly depending on what other optimization tricks the hex blades have i would not adjust the cr at all