I think the better question is what defines one card. Dijkstra is one card but he plays 2 one after the other. A combo like the one you described is definitely very powerful but it requires numerous cards to be played all one after the other. By that rational almost every single combo that is only activated last can count as one card. Dijkstra can be a very lucky draw or a very unlucky one. What is described in the OP also requires setup and luck. Menno into killing Letho is usually more consistent and under circumstances can be just as powerful. Kambi can bring a 100 point difference down to 20 but also requires setup. The Elder can sap a STR 40 axeman for a 44 point swing. but if we are talking strictly one card, without any dependence on the board then it's gotta be Ciri: Nova (which also requires setup, even if the setup is the deck itself)
But to play along, here is one other slightly less powerful combo:
Cahir -> Emhyr -> Vilgefortz (killing a vicovaro) -> Tibor Eggebracht - > draw a Vicovaro back
But to play along, here is one other slightly less powerful combo:
Cahir -> Emhyr -> Vilgefortz (killing a vicovaro) -> Tibor Eggebracht - > draw a Vicovaro back