omen & dead mans plate

I usually run deadman because the passive movement speed haha. But depending o wh you are fighting etc. Example if your the tank for your team and they have someone like jinx who is just gonna run past you to take down adc, squishy support, mage or something like tha I'd roll omens. But so say your darius top against someone AD i'd choose deadmans. I am biased towards deadmans though I love it.

want to teamfight and have an easiy way into the enemie team/ the enemie team trys to dive yours? Randuin's and the 4 sec aoe slow is your choice.

Want to roam/splitpush or have troubles ever reaching a target? Built up momentum with Deadman's Plate!

Deadman's is better if you're an initiator, Randuin's is better if you want to peel. Generally speaking anyway.

situational...yyou have to decide. Extra HP on deadman's is nice if you're gonna also build FH or thornmail.

if they have multiple champs with crit randuins...

also, what narasimha said