I have this that i want to implement with a homebrew warlock subclass, but I am struggling to put it in correctly so that it displays on the sheet right. If anyone can help me, it'd be much appreciated

Starting at 1st level, you are given the staff in a dream. When you wake, the staff is in your hand. In practice, you may use a bonus action to exert destructive energy from its eye. When doing this, you must roll a 1d6, which will determine the type of damage done. A chart will be provided below. At level 12, you gain full control of the staff’s power and can perform whichever damage you please at will.
The DC for this saving throw equals your Warlock spell save DC. A creature takes 2d8 damage on a failed save, and half as much on a successful one. The damage increases to 3d8 at 10th level.

• 1 - Acid - 5ft by 30ft line - Dexterity Saving throw
• 2 - Lightning - 5ft by 30ft line - Dexterity Saving throw
• 3 - Poison - 15ft cone - Constitution Saving throw
• 4 - Fire - 15ft cone - Dexterity Saving throw
• 5 - Cold - 15ft cone - Constitution Saving throw
• 6 - Your choice of the previous.

What is it you are trying to have it look like?

I would do this with an action for each option.