The plant pictured is Black Velvet Alocasia (Alocasia reginula) an Aroid (Araceae) native to Borneo. The leaf immediately behind it is Watermelon Peperomia (Peperomia argyreia), in the Black Pepper family (Piperaceae) and native to eastern Brazil.
A discolored leaf tip is not necessarily indicative of root rot, but do double-check that the plant is receiving proper care.
Alocasia reginula wants bright, indirect light, well-drained soil , regular irrigation, and occasional application of a complete fertilizer.