SUMMONING WEAPON / "INVOCATION" ENCHANTMENT

It would be great to have a weapon (Sword or Staff) or ENCHANTMENT that allows you to SUMMON the LAST entity or creature that we KILL using said weapon (just giving it the last hit will be enough), of course each invocation will cost EXPERIENCE (the amount the MOB drops plus a fifty%). The summoned entity or creature will not attack the player, nor will it follow you or defend you (unless the weapon has the LOYALTY enchantment). BOSSES cannot be summoned.