It's been a while, but we have another Incense Day on our hands in Pokémon GO. This Sunday, January 24th from 11 AM through 5 PM, Mareep Incense Day will see Mareep responding more frequently to Incense. There will also be alternating hours where Electric-type and Dragon-type Pokémon will respond to Incense. During past Incense Days, the focus species has had an increased Shiny rate, so this may be a terrific chance at getting Shiny Mareep, the cotton candy sheep.
Also during this Mareep Incense Day, evolving Mareep (or a Flaafy) up to the final stage of Ampharos will give Ampharos the Community Day exclusive Charged Attack of Dragon Pulse. This is going to be especially useful now because of the release of Mega Ampharos as a dual Electric/Dragon-type, which will now give Mega Ampharos a Dragon-type move with STAB (Same Type Attack Bonus).
Niantic announced the full details of the event on their official Pokémon GO blog:
In addition to Mareep, different Pokémon will be attracted to Incense at different times. During times that feature Electric-type Pokémon, you might encounter Pikachu, Magnemite, Voltorb, Chinchou, Mareep, Plusle, and Minun. If you're lucky, you might encounter a Stunfisk! During Dragon-type hours, Dragon-type Pokémon and Pokémon that evolve into Dragon-type Pokémon will be attracted to Incense, including Horsea, Dratini, Mareep, Trapinch, Vibrava, and Swablu. If you're lucky, you could encounter a Bagon! From 11:00 a.m. to 1:00 p.m.: Electric-type Pokémon From 1:00 p.m. to 2:00 p.m.: Dragon-type Pokémon and Pokémon that evolve into Dragon-type Pokémon From 2:00 p.m. to 4:00 p.m.: Electric-type Pokémon From 4:00 p.m. to 5:00 p.m.: Dragon-type Pokémon and Pokémon that evolve into Dragon-type Pokémon
In addition to all of this, there will be a free Incense bundle in the shop.
Good luck out there, fellow trainers! Personally, I find the entire Mareep line to be one of the most underrated in the game. Both Mareep and Ampharos are incredible Shinies and Ampharos is quite useful. Most of all, though, outside of the Shiny hunting, have fun!