How about a rogue who learns things?
You don’t need to be the quickest person, but you can be the smartest person in the room. Your goal is to find out how the world works. Now you’ve set off into the world to see what you can learn!
Starting at 3rd level, you can use the bonus action to make a Intelligence(religion), Intelligence(nature), or Intelligence(arcana) check (DC 8 + 1/2 creature CR). If you succeed, you can make an sneak attack against the target without advantage or another ally engaged with the target.
You gain proficiency in religion, nature, and arcana. You may change what skill you choose for your expertise ability
Starting at 9th level, you gain expertise in either perception or in investigation. If you have expertise in either of these, you can choose a different skill to gain expertise in.
By 13th level, if you have already succeed on a check using your study ability against a type of creature, you always can make a sneaks against that type of creature in the future. For example, succeeding against a black dragon would allow you to always make sneak attacks against black dragons in the future, but you would need to make the check against green dragons as they would be a different creature type.
When you reach 17th level, you can help your allies with the skills you have learned. Once per day, as a bonus action, you can give any number of a use of your sneak attack damage bonus dice against one creature that you have studied before or have used your document ability with. For one bonus action, you can designate as many creatures as you want against a single target. Each creature can use your sneak attack against one target. Additional bonus actions are need to choose different targets. The ability to make a sneak attack goes away after one minute. Multiple creatures can sneak attack the same target in a tern using this ability. You are limited to one of sneak attack a target a round as normal. You regain this ability after a long rest.