D&D 5E Blindsight homebrew spell

[auburn2]

What level would you make a spell that granted blimndsight to 30 feet for 1 hour?

Truesight is 6th level and is better than this would be in every way. I am guessing 4th level with an upcast to 8 hours for a 6th level slot or 24 hours for an 8th level slot? Does that sound about right?

The reason it is I play a warlock-assasin with devil's sight. A favorite tactic is darkness then wade and and attack everyone with advantage while they get disadvantage on attacking me. Problem is the rest of the party can't see in the darkness either. This doesn;t really hurt them in combat. They don't get disadvantage. The enemies can't see them giving them advantage on the attack, while they can't see the enemies so they have disadvantage on the attack - so these cancel and make it a straight role. However not being able to see the enemy or each other causes of other problems. What we would like to do is cast a blindsight spell on the fighter so he gets advantage too and it is easier for us to coordinate.

 

[Hawk Diesel]

Yea, it sounds about right. Darkvision is a 2nd level spell, so I'd say 4th level is a good sweet spot between that and True Seeing at 6th. It might be better to include more targets of the spell with upcasting rather than increasing the duration, though both work fine. You would also want to define if the blindsight works via sound like a bat or is more like tremor sense.

Out of curiosity, what does the DM, the other players, and their characters think about the strategy? I mean it is a legitimate and fairly common strategy for a warlock, but obviously it is also a double-edged sword. It might be worth trying to find, or perhaps even trying to create a pair of goggles that provide devil sight. I don't recall their being any official item, but if the tactic causes problems the DM might be willing to work on helping to create a solution that doesn't nerf your character, but also doesn't hurt the others.

But if you are concerned about this, it might be easier (and it's the same level as what you propose) to take Greater Invisibility as a 4th level spell. It's not technically a Warlock spell, but reflavor it as "Armor of Darkness" and it would easily fit the bill.