Creating an incremental database copy using RMAN:

RUN {
    CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET;
    BACKUP INCREMENTAL LEVEL 0 DATABASE PLUS ARCHIVELOG TAG "LEVEL 0";
    BACKUP CURRENT CONTROLFILE SPFILE;
}

BACKUP INCREMENTAL LEVEL 1 DATABASE PLUS ARCHIVELOG TAG "LEVEL 1";

Create a cumulative (includes changes reflected in incremental backups) backup with level 1

RMAN> backup incremental level 1 cumulative database;

// Reset database to incarnation 3

RMAN> reset database to incarnation 3;