An attack is not the same as a hit.
And water is wet.
This varies based on AC, but an attack is only worth maybe .7 of a hit on average and a lot less than that on a very high AC enemy where Bless is at its best.
Not necessarily. If you don't hit a lot anyway, instead of trying to hit AC, casting a spell that forces a save or deals automatic damage might be better.
If you increase your chances to hit from 5% to 17.5% you still suck at hitting.
For example: 8th level Cleric fighting a 22AC enemy:
An extreme outlier, but go on.
Cleric Swings his axe for 12 damage on a hit (1d8+1d8+3) with a +6 attack. His DPR is 3. He loses 3 damage in round 1 casting bless.
Yeah. No good idea to attack.
After he casts bless his DPR goes up from 3 to 3.9 so, so in a 3 round fight he does 7.8 vs 9 damage so it cost a little more than a hit point of damage for him to cast bless.
Sure. Sounds like the cleric understands the game.
The fighters he cast it on get 4 attacks a round combined (if they don't action surge). At 8th level they are doing 12 damage too and are doing it with a +8. So their DPR is 8.4 (two attacks). With bless it goes up to 10.2. That is each, so overall it is 16.8 vs 20.4. per round.
Ok. So against hypothetical enemy that has AC 22 and 65 HP, you win over 3 instead of 4 rounds.
Congratulations. You really outsmarted the DM.
So in the very first round they have already made up everything the Cleric lost casting Bless. Over the course of 3 rounds the damage is 59.4 no bless vs 69 with bless.
Oh no, if the enemy has 70 HP, that does not save you a single round.
This also does not consider weapon masteries or damage buffs or anything else that would make the numbers even bigger and it doesn't consider the save bonus you get either.
Correct. If you get a weapon mastery hit in, that might help. Except for graze, which deals damage on a miss, and which is extremely good in this situation.
This is a legit question. I don't think a Cleric Cantrip is generally going to do better in tier 2 unless the enemy is already damaged and has a very weak Wisdom save. Other leveled spells might work better, but other first level spells using a first level slot only situationally so.
Yeah. Level 1 cleric concentration spells are not that great.
Magic Missile is a pretty solid 1st level spell especially against a high AC, if the Cleric has it and casts it round 1 vs that 22AC baddie that is 66.9 vs 69.
And it does not cost concentration.
Witchbolt is a good 1st level spell. If he casts that on round 1 65.5 vs 69
It targets AC, so I would hesitate to use it here.
Chromatic Orb is a solid spell generally, assuming 2 enemies is 61.7 vs 69.
Same.
Guiding Bolt which is the only one of these options most Clerics have is 62.2 vs 69
Same.
So. Lets sum it up:
Bless just allowed you to deal 20% more damage in a combat against a very high AC foe.
The net benefit however was just 10 damage which can be made up by a single cast of magic missile not costing concentration which might get broken or needed otherwise.
Weapon masteries might have a positive effect, but also a negative (graze!) on the calculations.
So if that enemy is a spellcaster that targets the party's saves a lot, bless is great here. If the fighters use topple mastery, getting a single hit in allows for attacks with advantage afterwards. A very good combination. Now you start hitting a lot despite the high AC.
But still the question is: would it have been better to cast hold person on the enemy, granting advantage and automatic crits to the fighters on the failed save? A level 8 cleric probably has a spell save DC of 15. A fighter type enemy sometimes has less than +0 on their wisdom saves. That is a 70% chance to paralyze the target, probably ending the fight right there if the enemy just has 70hp.
And since the enemy did not hit bqck and wounded your fighters, it might not even be a higher spell slot investment, because you save up healing resources (which might be needed or not).
TLDR Is it a bad spell? No. Not by far. Is it overrated? Yes. Because it is often best in situations where a different tactic yields way better results.