This could be the senjutsu equivalent of the Susanoo. This jutsu requires the "Sage Group's Gift Chakra", which is basically "Sage Chakra". Senjutsu and dojutsu are hinted to be equivalents when: Jiraiya (senjutsu) vs Six Paths of Pain (dojutsu), Naruto (senjutsu) vs Six Paths of Pain (dojutsu), Naruto (senjutsu) vs Sasuke (dojutsu), and Sasuke/Itachi (dojutsu) vs Kabuto (senjutsu).
When dojutsu has a chakra battle avatar (Susanoo), senjutsu has to have a battle avatar as well, and this is where this jutsu comes in. This jutsu summons a yellow Buddha thing, and yellow is the colour of senjutsu chakra. Naruto has Kurama to create the battle avatar, but how about Asura? His battle avatar doesn't look anything like any Tailed Beast. So we can assume that it's this jutsu, because Asura inherited the senjutsu part of Hagoromo, and with senjutsu he can create it. His avatar is not a Buddha, but something else, like how Susanoo differs between each person.
How Chiriku got this jutsu? We'll, monks meditate, like how you achieve Sage Mode. Maybe the monks can achieve a stage where they can utilise senjutsu, but can't achieve Sage Mode. Or, the monks are trained under an Uzumaki member, who became their master. This also explains why the monks know how to use Tailed Beast Chakra Seal, which as the name says, a sealing method to seal Tailed Beasts, something Uzumaki Clan is well known for. Or, maybe Chiriku is from the Uzumaki Clan, and because he doesn't have hair, we don't know.