fix #8097,

the sacrifice target cost was optional, but SacrificeCost.canPay first checks if there are valid targets. In this scenario there were none, but the spell should still be playable

Mage/src/main/java/mage/abilities/costs/common/SacrificeTargetCost.java

@@ -87,6 +87,10 @@ public class SacrificeTargetCost extends CostImpl {
                 }
             }
         }
+        // solves issue #8097, if a sacrifice cost is optional and you don't have valid targets, then the cost can be paid
+        if(validTargets == 0 && targets.get(0).getMinNumberOfTargets() == 0){
+            return true;
+        }
         return false;
     }