Arc of Lightning 3rd lvl Cleric Spell - Is this incredibly overpowered?

[King_Stannis]

We just switched over to C&C and one of my players is a cleric who has the Adventurers Spellbook. They cast Arcane Lightning for the first time and apparently the damage dealt is fixed to the caster's current HIT POINTS. It was the start of combat so the priest had 40hp. Save for half. Still, a guaranteed 40 on enemies in the line of fire who fail in this system seems utterly insane. Especially for a 3rd level spell. I thought for a minute D&D 5e had tried some sort of Invasion, as it seems more at home there.

Am I reading this wrong?

[Go0gleplex]

It is a pretty powerful spell...but you have to look at it a bit more objectively. The key phrase here is 'current hit points'. The cleric was a max health and used the spell in its best condition. A few rounds of combat later and it could've been a totally different outcome depending on how many foes attacked and hit. Say the cleric took more than 50% of his HP in damage before using it...so less than 20 points at that time which is more in line with a Fireball spell in damage range. Further tally in that unless the enemy is stupid or in a confined space, they only have to spread out and said damage is limited to one or two enemies. Also, being a 3rd level spell, means at least a 5th level cleric to be able to cast it whom would have 55 HP if rolling all 8's with an 18 CON. Even without the CON bonus 40 hp is max for the level...which is a bit unusual for most characters whom would typically range between 28-38 HP with a nominal CON bonus which isn't that far off of a max damage fireball. So...much more of a conditionally powerful spell more than being overly powerful IMO.

Now consider spells of a couple other classes. Illusionist has Major Image, which if used creatively and correctly, is a certified ARMY killer...at only 3rd level. Druids have Call Lightning which does 5d10 with each of several attacks if outdoors.

[King_Stannis]

Would the spell affect friendlies who happen to be caught in the path?

[King_Stannis]

We ended up doing D6 per level here for this spell. It ended up working pretty good. This way the DM doesn't artificially go after the Cleric in the first round to get their HP down. The cleric would be an absolute fool not to stand in the back and blast the toughest enemy on round one.