As part of the plan to leave Marit Lage on Amonkhet with the undead as worshippers, Jace had claimed he would create a thought-copy of himself as bait, since he was the beacon Marit Lage navigated after
Play it to pad out your curve, bring up your numbers or hedge against bad matchups
Other good payoffs for this strategy include Liliana, Dreadhorde General for incidental card draw, Moldervine Reclamation for lifegain, and Grave Pact for board-wide punishment
One mana is a steal, however, as shown by cards like Blasphemous Act
They buy in bulk, pick up mid-value singles, and sometimes purchase entire collections if the price makes sense
Its like a much more functional The Phasing of Zhalfir, and at least in Eternal formats I think thats a card we all benefit from