Trying to copy this feature into the Homebrew. I’m having trouble finding a suitable way of doing so. Here’s the link (X)

I would help you, but I don’t follow external links. If you can show me what you want without the external link….

Here’s the text: 

Starting at 3rd level, you have learned to unleash bolts of necrotic energy from within your revived body. Immediately after you use your Cunning Action, you can make a ranged spell attack against a creature within 30 feet of you, provided you haven't used your Sneak Attack this turn. You are proficient with it, and you add your Dexterity modifier to its attack and damage rolls. A creature hit by this attack takes necrotic damage equal to your Sneak Attack. This uses your Sneak Attack for the turn.

Thanks in advance!

Create the class feature and attach a Spell Action to it. Set it up like this:

Then edit that new action and add “Level Overrides” to it to increase the damage at the appropriate levels.