Samorukov, 23, was originally drafted by the Oilers in the third round (No. 84 overall) of the 2017 NHL Draft.
Last season, the 6-foot-3, 188-pound defenseman dressed in 51 games for the AHL's Bakersfield Condors, recording 18 points (three goals, 15 assists) and 44 penalty minutes. The Volgograd, Russia, native also made his NHL debut on Dec. 29 against the Blues.
Overall, Samorukov has collected 30 points (five goals, 25 assists) and 70 penalty minutes across 103 career AHL regular-season games.
Kostin, 23, appeared in 40 regular-season games with the Blues last season, tallying nine points (four goals, five assists) and 23 penalty minutes. The Penza, Russia, native also totaled six points (three goals, three assists) and 15 penalty minutes in 17 regular-season games with the Blues' AHL affiliate, the Springfield Thunderbirds.
