The CW has released the description for the May 11th installment of Arrow titled "Monument Point".
Season 4 Episode 21 "Monument Point"
TOM AMANDES RETURNS AS NOAH KUTTLER
When Team Arrow learns what Damien Darhk’s (guest star Neal McDonough) next move is Felicity (Emily Bett Rickards) realizes she needs to ask her father, Noah Kuttler (guest star Tom Amandes), for help. Noah and Oliver (Stephen Amell) have a heart to heart talk that leaves Oliver rattled.
Oliver (Stephen Amell)
Felicity (Emily Bett Rickards)
guest & recurring cast:
Damien Darhk (Neal McDonough)
Noah Kuttler (Tom Amandes)