Transformation
The author describes Sniffers digging into Sculk becoming infected. After 30 seconds they transform into a Dark Sniffer. This is mod behavior, not a documented vanilla transformation.
Behavior
Dark Sniffers can dig up Sculkflower Seeds and use a “Sonic Sniff” to pull targets closer. The author also describes a rare calm interaction with Wardens. Exact combat numbers are not supplied on the project page, so they are omitted here.
Where to learn more
Read the author’s project description for any later changes, and verify your installed file in the version checker before assuming the behavior applies.