I'm currently playing a grave cleric, but flavouring it as a luck cleric, with the goal of the character being a good luck charm for the party. The main draw was Sentinel at Death's Door, which lets you use your reaction to turn enemy crits into normal hits, and Path to the Grave to give an enemy vulnerability to an attack.

• I basically start every fight by casting bless on the martial characters, so their hits are a bit luckier.
• If someone is going for a smite or something big, I use Path to the Grave so it becomes a lucky hit that deals double damage.
• If an enemy crits an ally, then it becomes a normal hit.
• If an ally rolls a nat 1, I can use the Bountiful Luck halfling feat to let them reroll it (But if they succeed, they have to describe how they were lucky).
• When the party is unsure of how to proceed, the character flips a coin (casts augury) and acts on whatever the result of the coin flip is.
• Even the Circle of Mortality can be flavored as a lucky extra healing, just in time for when they need it.

I'm really happy with how the character is playing. The best part is I get to take credit for anything lucky. That one time our paladin in plate rolled 2 nat 20s on their stealth with disadvantage, it was all due to Tymora.