The new events are on now, with the Season 14, Children of Lilith Battle Pass available. This new pass has 40 ranks of challenges and rewards to complete. Among those rewards are the Mother’s Lament Two-Star Legendary Gem, the new Legendary Gem in Diablo Immortal. If you get your hands on one of these, you’ll have a 20% chance to get Maternal Disdain. When you have that active, your critical hit chance goes up by 32% for 6 seconds. When Maternal disdain ends, your advantages aren’t over. You will release a blood spike towards nearby enemies, dealing 54% base damage and applying Bleed to enemies hit.
While that is a pretty sweet deal, there's a lot more to take advantage of. In the Diablo IV crossover, the huge world boss Ashava makes her way over to Diablo Immortal. If you are at least 30, you'll have a chance to take her on. If you successfully kill her then you will earn 10 Marks of Pestilence. You can do this once per day, also earning one Telluric Pearl, 50 scrap materials, and three Enchanted Dusts.
Each Mark of Pestilence is worth one random reward. Or save up 88 of them for a one-time only trade to earn a random Legendary item. Collectively, each server has the chance to rack up rewards for all who slay Ashava and trade in their Marks. The rewards go from a collective 888,888 Marks traded in for 20 Aspirant’s Keys, to 6,888,888 Marks traded in for a Mother’s Lament Two-Star Legendary Gem. As you can see, there's more than one way to get one of the new gems, but it won't be easy.
The Phantom Market is also back,offering a Lilith Cosmetic Set in exchange for Obols you can buy with Eternal Orbs. Your first pull from the set is free though.
For more on the event, see the announcement at Diablo Immortal.