Dead by Daylight

This achievement is awarded for injuring or downing a survivor in basement meaning that camping the basement to get this out the way is your best friend. The new perks with sable also mean more survivors will be in basement.

The way to get this without having to buy any character would be to play
- Hag (placing traps in basement)
- Trapper (traps injure survivors and/or down with add ons)
- Wraith (high map mobility and stealth to camp)
- Huntress (Able to get 2 hits in a very short duration by throwing hatchet then basic attacking)

The best way to get this with dlc's would be
- Legion (Power hits multiple survivors at once)
- Trickster (knives have a high injure time when aiming at a person unhooking)
- Dredge (Teleport to lockers at basement)

I'd recommend these killers for their abilities to get very easy hits or down in the time on being in basement

Now going with these recommendation I'm going to play Wraith due to the stealth mechanic with his bell, the build i will be using consists of Agitation (The trapper), Iron grasp (Base perk) and 2 random perks but i took for the sake of getting this without transaction Brutal strength (Trapper) and Enduring (The Hillbilly). I brought the offering "Torn Blueprint".

The method i used, Using the perks given i got my first down and with increase carrying speed plus time i got the survivor to the main building basement since my offering guarantees this spawn, With wraith i went invisible and waited just outside the basement around 8-16 meters away (Anti-camp prevention), wait for another survivor to run into basement, followed them in, uncloaked, hit to injured and as the survivor unhooks i downed them for 8% progression i continued doing this for the rest of the achievement, 4% each hit.

Depending on survivor behaviour this can be done in around 2-6 games

The achievement description is misleading. It makes it sound like you can only make survivors go from Healthy to Injured to count towards it, but in actual fact they can be already Injured. Basically the achievement just requires you to hit survivors in the basement 25 times whether healthy or injured.
That being said, I found a funny strategy to make this happen though it's slow and not guaranteed.
Basically, from the start of the match just sit in the basement and wait for survivors to come to you. Naturally, when the killer hasn't been chasing anyone and what have you, survivors tend to get curious. Eventually they'll come check out what you're doing.
You could put on Insidious for this but honestly I wouldn't recommend it. Hearing the terror radius will help draw them in.

Of course, you could always just play a killer with a basement build like Trapper or Bubba, but that's up to you.