Antisune
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R U2 R' U' R U' R'7 moves · R and U only
How to recognise it
Only one corner shows yellow on top. Hold it at back right: the front-left corner's yellow sticker faces you.
Its inverse is another case
Do the Antisune algorithm backwards, R U R' U R U2 R', and you are solving Sune.
That's why CubeDojo never scrambles Antisune that way: it builds a random state with the case fixed, so you practise Antisune and not Sune.
Practise Antisune now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.