Mirror of the Forebears [Dragon Deck]: Any artifact that can go into any tribal deck
(Choose any number of permanents and/or players, then give each another counter of each kind already there.) When you proliferate, you can choose any permanent that has a counter, including ones controlled by opponents
But it is a mana cheaper to do so, and will immediately reward you with another card to discard so you can move onto your main plan
If you discard a card while you control Necrodominance, abilities that function when a card is discarded (such as madness) still work, even though that card never reaches your graveyard
Needless to say, while it may be challenging to set an accurate value, these cards are becoming more valuable with each sale, as they're often stashed in personal collections when sold
In fact, there's so much math involved in determining this, I won't even try to understand that