All permanents on the battlefield (Sakashima of a Thousand Faces as a copy of Boonweaver Giant).
Next of Kin attached to Sakashima of a Thousand Faces.
Steps
Activate Phyrexian Altar by sacrificing Sakashima of a Thousand Faces, adding one mana of any color.
When Sakashima of a Thousand Faces dies, Enduring Renewal and Next of Kin trigger.
Resolve the Enduring Renewal trigger, returning Sakashima of a Thousand Faces to your hand from your graveyard.
Resolve the Next of Kin trigger, putting Sakashima of a Thousand Faces from your hand onto the battlefield as a copy of Boonweaver Giant.
When Sakashima of a Thousand Faces enters the battlefield, it triggers, returning Next of Kin from your graveyard to the battlefield attached to Sakashima of a Thousand Faces.