'Pokemon Go' Swinub Incense Day: Which Pokemon Players will be Encountering and More
To start its "Season of Heritage," Pokemon Go will launch its "Incense Day," an event where a specific set of Pokemon that are in the wild will become attracted to the Incense item. For this event, Swinub will be the featured Pokemon that will be attracted to the said item, as well as several Ice and Ground-type Pokemon.
Source: gamenguide.com