Is the Graviturgy Magic wizard's Adjust Density feature overpowered?

Question

In the Explorer's Guide to Wildemount, there are two new arcane traditions for wizards: Graviturgy Magic and Chronurgy Magic.

The Graviturgy Magic wizard gets the Adjust Density feature at 2nd level when they choose the tradition (EGtW, p. 185):

As an action, you can magically alter the weight of one object or creature you can see within 30 feet of you. The object or creature must be Large or smaller. The target's weight is halved or doubled for up to 1 minute or until your concentration ends (as if you were concentrating on a spell).

While the weight of a creature is halved by this effect, the creature's speed increases by 10 feet, it can jump twice as far as normal, and it has disadvantage on Strength checks and Strength saving throws. While the weight of a creature is doubled by this effect, the creature's speed is reduced by 10 feet, and it has advantage on Strength checks and Strength saving throws.

I'm still pretty new to D&D and its rules, so this confused me. It seems like a variant of the enlarge/reduce spell, but it doesn't require any spell slots or a saving throw to prevent it from affecting an unwilling target.

I'm new to being a DM and I'm not sure how OP something like this would be at 2nd level. It could completely turn combats on their head if they use Adjust Density against an attacker whose attacks are based on Strength.

I have two questions about the Adjust Density feature:

• Is this OP compared to other 2nd-level abilities?
• What can I do to prevent battles being turned on their head by this magic feature?

Answer 1

It doesn't really disable a Strength based attacker

This appears to be the main concern you have, and the important distinction is that it affects ability checks and saving throws, not attacks. Ability checks, saving throws and attack rolls are distinct (a feature referring to one does not automatically include the other) even if the seem quite similar (all a resolved by rolling a d20, adding a bonus and comparing to a number).

The feature does make pushing and prone-ing slightly easier (at the cost of additional actions), but this is not game breaking and not out of line compared to the second level feature of other wizard subclasses.

Answer 2

The main use I can see for this ability is to assist a grappler in your party. Something with high strength and low dexterity can be given disadvantage for the grappling check. Or, if a party member isn't a raging barbarian, give them advantage on their strength check instead.

Otherwise, the speed boost or penalty is more of a ribbon ability as its not worth spell concentration.