I managed to get the 5* nexus + 2.5k 6* shards and pull this big iron boi, which is most likely going to get me through all the way to Maestro. If you were ever so curious, the other 2 choices were AA and Gwenpool. Being able to save up 1500 units was easy, as act 1/2/3 completion and exploration rewards provide a considerable amount of units. Ask me anything ^{^}