Here's the situation. In the campaign that I am DMing, I have ruled that if a blessed creature (via the Bless spell) gets a total of 20 (or more) on the sum of the d20 and the d4 on an attack roll, that counts as a critical hit. My question is essentially, does this house-rule allow bless to remain balanced against other spells of a similar level?
I did the math and this increases your odds of critting from 5% to 17.5% and from 9.75% to 31.625%(!) with 5e's advantage. This rule would also mean that a blessed creature cannot crit fail.
Things to consider: (note, none of these have come up yet in the campaign but I would rule this way if/when they do)
Bardic Inspiration: Bardic inspiration would also increase your chance of critting
Bane: Bane would make it impossible to crit (unless also blessed, or inspired)
- Any other ability that lets you add dice to an attack roll that I am forgetting.
Is this balanced? Are their any consequences of this that I am not seeing?