Split Cards The split cards first showed up in Invasion block and take the choose-one modal theme to the visual extreme, displaying it as two different miniature cards
The Gaffer gave us the 3 or more life clause, and Haliya came along with Edge of Eternities to give us a Soul Sister in the zone, that also draws cards, which is pretty neat
To make things fair, sideboards are generally limited to a maximum of 15 cards
Each of these new forms gives Viconia, Nightsingers Disciple added utility from its ability to exile cards from graveyards
Solemn Simulacrum is likely one of the better cards for this purpose too, you are just trying to delay or force them to over extend into a Wrath
The last new cards I want to acknowledge are not creatures and aren't related to dragons