MN 18, the Madhupiṇḍika Sutta (among many others) defines phassa within the context of paṭiccasamuppāda by way of the familiar tiṇṇaṁ saṅgati formula, whereas DN 15, the Mahānidāna Sutta, on the other hand, subscribes to the aññamaññapaccayatā model.
(Bucknell distinguishes nicely between these two here.)
Both are very much distinct from the twelve-linked chain’s phassa, obviously.
My question is: What does the Visuddhimagga teach (especially with respect to the first two)?