Spellman, 24, is 6-foot-8 and was drafted by the Hawks with the final pick of the first round (No. 38 overall) in 2018.
A native of Cleveland, Spellman has appeared in 95 NBA games, ranging from 2018-20, a season each with the Hawks and Warriors.
He most recently played for the Warriors during the 2019-20 season, appearing in 49 games and averaging 7.6 points and 4.5 rebounds, while shooting 43 percent from the field.
He has bounced around a little since then, but has yet to appear in another NBA game.
“Spellman was later flipped to the Timberwolves at the 2020 deadline in the Andrew Wiggins/D’Angelo Russell trade, then was sent to the Knicks last November,” noted Luke Adams of Hoops Rumors. “He began the 2020/21 season on New York’s roster, but was waived in January to make room for Taj Gibson.”