Relic Shield Passive with Kalista and Souldbound Thresh

As Thresh, while southbound to Kalista, Relic Shield passive is unable to proc when it kills a minion that has the passive damage bonus for attacking the same unit as Kalista. Killing a unit gives Thresh +1 gold, but does not proc the passive of Relic Shield. Pretty much renders the item useless if supporting Kalista and soul bound.