Dragon Horn max jump of 3

That seems to be address 21A350 (or E1/A150). Just remove your zero from the end. The code you are searching for is

C9 10 B0 03 EE 70 3A

Also, note that I haven't tested this code. The line that I'm not sure about is the "C9 10" (aka CMP #$10). If it's not working, a quick-and-dirty solution would be just to replace the last 3 bytes with EA. That way, whether you branch or not, it won't add an attack.