Mix this and Frozen Heart on Nasus and watch your enemies cry

^^ I think, as the passive is titled cold steel on this, and it isn't on the frozen heart. I suggest testing it.

does it stakc with frozen heart?

Sadly, there is no Force of Nature anymore...

Randuin's Omen+Force of Nature+Warmgog's Armor=U can't die!!
Awesome item!

Does anyone know how the mechanics work with stacking, in other words, how it is computed relative to the enemy's attack speed?

For instance, take Lee Sin's Tempest/Cripple and apply it, then using Randuin's Omen's Active, does that reduce by 35% of their current movement/attack speed after Cripple, or is it another 35% reduction off their base speeds, stacking for an effective 95% if proc'd together.

In the first case, would it then be more effective to use Randuin's before applying cripple?

I like use this on tanks who have a "taunt" skill, or on duelist to make me have advantage 1vs1

i like how it has a chance to slow attackers not the defender like most items

It is worth it even without the active, the passive and the stat bonuses are insane.

Is this Item worth it even w/o the active?? When I get this Item I usually 4get to use that Active! Nevertheless, this item is just an overall awesome tank item (: ..

That is correct Keels.
At 99 armor and 99 magic resist, you get no bonus seconds.
At 100 armor and 99 magic resist, you get 0.5 bonus seconds.
At 100 armor and 100 magic resist, you get 1 bonus second.

so say I get 100 armor and 99 mr. Do I still get the .5? Do I get 1 second additional if i have both 100 armor and magic resist?