Dark Harvest change looks good, since some levels of ARAM apparently suffer from it greatly.
I really don't like removal of Warmog though, since what are the tanks supposed to do without it; take the poking and die? Loss of Warmog gives even more power to the poke comps than they already have.
The new items:
Those Kaynwalkers (I already call them that, because they are like an improved Kayn wallwalking) appear to be potentially too powerful. They allow any melee guy to get behind their ranged enemies unless they keep hiding behind the turret(s). Are the Tanks supposed to use those to get to the enemy and do their thing assassinlike (do they still have the health left when they do that?)? And what will the assassins do with those? (Granted; Assassins are generally weak in ARAM and could use a power boost, so I am not complaining about that - much).
Bloodletter's Veil: AP Assassin boost, and some mages might like it too. Not bad.
Spectral Cutlass: In hands of an assassin this can be handy and thus I am not complaining (I suck with assassins, but many of them do need more power in the Abyss). In hands of ADCs, these can result in weird fights. "Wasn't that Jhin there just four seconds ago??" Jhin will love it just the time delay it has at least. :)