Obviously a holding tool is better than using a coin but if you are stuck this works. You don't need an impact tool, a breaker bar will get it off. However it's very f'n tight.
yes, can be very tight and the fact it's such a shallow nut it needs a good fitting full-hex socket with the starting chamfer ground off. I think we all started using a breaker bar but both the need to restrain the crankshaft plus the risk of slipping on the shallow nut can both be removed with above impact gun.