What do I do about this damaged internal corner?

[Regis]

My lockdown project has taken on a life of its own and after years of painting over the terrible wallpaper in my hall, I’m now removing it. Most of the plaster underneath is surprisingly sound, if a bit rough.
However, this one corner is in particularly bad shape (see photo).

How should I approach this? I’m not great at skimming (literally the hardest thing I’ve ever attempted), but going to have a go before inevitably calling in a pro, but not sure what is best to sort out the corner first.

Just filler or something better?

 

[dontbelieveawordofit]

https://www.toolstation.com/toupret...MI9KPk98qj7QIVFK-yCh1c4wCFEAQYASABEgI13fD_BwE

skimming skills not needed.
rubs back lovely.
although the neater you get it on the less you have to rub back.

 

[Regis]

Nice. I have the toupret fine surface filler which is pretty amazing so good to know this is quality as well. “No thickness limitation” - excellent. Thank you!