Landslide for outlaw, ds for subive used double ds and double landslide and I can say for sub I would take dancing steel. it almost always double procs in openers compared to double landslide where I would rarely get 1 proc in my opener. landslide is a lot more ap but just didnt seem to proc when I needed it to, your experience with it might be different though.
This is a good explanation as to why landslide is only really the best when it comes to outlawDancing Steel procs off of poisons (this could be all nature damage sources but I'm not sure) and heal ticks (though not leech) as well as autos and melee abilities.
Landslide seems to be limited to proccing off of physical damage only.