When you get hella fed but can't carry

I can understand the synergy behind cleaver, but I personally prefer the mixed tankiness provided from sunfire and the magic dmg over the extra damage. Especially because Sion is a frontliner tank so he shouldn't really be able to damage the enemy frontline yaknow? If he was a diver I'd understand.

I almost never say no to zzrot either, just because it pays for itself in part and it provides great stall/push power for your team and works in almost any game. I just love zzrot in general.

Iceborn helps make up for the damage lost by not taking Titanic while not losing any significant stats/utility by not building Mallet imo, but I could be wrong.

I sometimes build GA but often times find myself with a Banshees or Titanic (usually banshees) simply because by the time I die and respawn again, the fight is likely to be over.

To each his own though :p