Duncan Keith Trades - CapFriendly - NHL Salary Caps
2022 conditional 3rd round pick* (EDM)
*Conditions: If the Oilers make it to the 2022 Stanley Cup Finals and Keith is top 4 in playoffs TOI during the first 3 rounds, the pick upgrades to a 2022 2nd round
So they went and encumbered their 2022 2nd and 3rd picks, and thusly can't use either in further trades (at least without some further conditions agreeable to the potential future trading partner that cater for the eventualities where they won't have the pick in question) or as offer sheet compensation.