I can’t find a reliable description of the Linker rank 3 spell.
On the ToS Wiki (which is outdated pretty bad), the description is: “Transferred Physical Defense Character DEF | Transferred HP Recovery Character HP Recovery | Duration 30 Seconds”.
On ToSbase, the description is: “Use the higher ability between you and ally linked by Spiritual Chain”.
The only way I can interrupt this is that it you give each other the the highest primary stats between you and your ally, so if your linked partner has 70 Int and you have 100 Int, than your partner would also get 100 Int. Is this how it works?