Pokémon Go ‘A Mystic Hero’ Timed, Special Research quest steps and rewards
Blanche needs your help! As well as evolution bonuses, completing A Mystic Hero research sees you receive a Lapras as your reward.
This article references relevant content from the polygon.com website. Original article link: [https://www.polygon.com/pokemon-go-guide/23681503/a-mystic-hero-timed-research-special-research]

“A Mystic Hero” is a Blanche-themed set of quests in Pokémon Go as part of the season-long Rising Heroes storyline.
Running April 13-17, though there are no event-specific spawns, you can expect two research quests — one Timed, one Special with no end date — as well as bonuses when evolving Pokémon.
Pokémon Go A Mystic Hero Timed Research quest steps
The following research steps — found on the ‘Today’ screen — will be available until the event concludes on April 17 at 8 p.m. local time:
Rewards: 1,000 XP, 500 Stardust, 2 Rare Candy
Rewards: 2,000 XP, 1,000 Stardust, 2 Rare Candy
Rewards: 3,000 XP, 2,000 Stardust, Magnetic Lure Module
Pokémon Go A Mystic Hero Special Research quest steps
The following research steps — found on the ‘Special’ screen — has no end date, provided you have logged in and begun the quest during the event:
Rewards: 1,500 XP, Eevee encounter
Rewards: 2,000 XP, Karrablast encounter
Rewards: 2,500 XP, Lapras wearing a Blanche-themed accessory Encounter
Thanks to Amiibofan101 on the Silph Road subreddit for filling in the gaps for this and the Special Research quest steps.

Pokémon Go A Mystic Hero Field Research and rewards
Thanks to the Silph Road research tasks list for the above.
Pokémon Go A Mystic Hero event bonuses
The following bonuses will be available April 13-17:
Beyond that, there are no special spawns, changes to Eggs or Raid line-ups as part of the event, which means the above bonuses and quests are your focus.