Be careful with 214-a, most characters can interrupt it easily. Try to gatling it from moves not anticipated. Examples:
-2a, 2b, 214d-a
-2a, 2a, 214d-a
-j.2c, land, 214d-a
-2a, 5b, 665b, 214d-a
The list goes on..
Another thing to consider is using 214d-d, backdash, 3c, after a predictable blockstring (ie:2a, 5b, 3c~), if they're predicting 214-a, you can get a CH 3c and net a juicy combo.