Originally Posted by konfetarius
I don't see how this item helps Rammus at all.
What's the point of slow when they are taunted? Rammus isn't the kind of champion that weaves autoattacks and spells, you powerball into target and turn all of his spells on at the same time. Unless the AoE is huge for this slow, it's not going to help his ultimate either.
Well, for starters, the AoE slow will be great for following up into teamfights. Not to mention, 15% CDR reduction and a 125% boost to one of his autoattacks (which even for his base damage isn't necessarily small). AS an AoE.
After using an ability, your next basic attack deals bonus physical damage equal to 125% of your base Attack Damage to surrounding enemies and creates a field for 3 seconds that slows enemies inside by 35% - 2 second cooldown.
On top of giving him armor and AP of course. AP, AD, and Tank Rammus (the unconventional build) will be strong as hell. The point of the slow is that usually when Rammus goes into taunt initially teamfights ensue. Now, factor that into Rammus already having low cooldowns in the first place, you can initally rush into a team with Powerball, and keep them almost perma-CC'd. Powerball into a group, AoE slow them, autoattack once, slow them again for 3 seconds plus do AoE damage, taunt one person, autoattack, slow AoE damage again (because a 2 second cooldown means nothing to Rammus when you have to factor him going into DBC again xD), Rinse, Wash, Repeat.
The item effectively turns Rammus into an AoE ball of goodness. Now, couple that with Frozen Heart, and GO WILD.
Or better yet, think Alistar.