12th and 13th Incarnations of the Lord...

Verse 1.3.17: Avatar means descend, coming down.
One point to remember: 19th and 20th, the incarnations are Krishna and Balarama Themselves. Here it is the Avatari Himself, Krishna the svayam bhagavan who appears.

Coming to today's verse: 12th and 13th Incarnation. Dhanvantari, an incarnation of Krishna, appeared during the churning of the ocean. And the 13th, as Mohini Murthy, Krishna comes just to bewilder the demons and share the nectar only with devotees.

Srila Prabhupada: Anybody who gets bewildered by lust, they can get rid of it by meditating on the deity form of Krishna (taking darshan from the lotus feet, slowly progressing towards the face, while continuously meditating or praying to the Lord) and focusing on the lotus feet of Krishna.