Thinking About Frozen Mallet in Comparison to its Sister Item.
You all the know the Frozen Mallet. It's that item that gives a good slow and a buttload of HP and a little AD on the side. Despite this, almost nobody builds it. I believe it has the same problem Ryali's had before it had its ratios changed. And, with this is mind, let's look at the differences between Crystal Scepter and Mallet.
-- Ryali's Crystal Scepter (2900g)
Build: Giant's Belt (1000g) + Amplifying Tome (435g) + Blasting Wand (860g) + 605g
Stats: +100 Ability Power, +400 Health
Passive: Dealing spell damage slows the target's movement speed by 35% for 1.5 seconds (15% for multi-target and damage-over-time spells).
--Frozen Mallet (3300g)
Build: Giant's Belt (1000g) + Ruby Crystal (400g) + Pickaxe (875g) +1025
Stats: +30 Attack Damage, +700 Health
Passive: Your basic attacks slow your target's Movement Speed by 40% for 1.5 seconds (30% slow for ranged attacks).
Let's talk first about build path.
With Ryali's, you build a two damage items- one low price and one medium price, with a semi-expensive health item. With Frozen Mallet, however, you build both a low and high price health item, but only purchase one medium-price damage item. Even before completing the item, Frozen Mallet gives a lot more health and much less offensive power. In addition, completing FM takes 400g more to purchase. Now, stats are stats and Mallet's passive could make up for the higher price point, and having a more health-oriented build path isn't exactly a bad thing... However, in this case, where the item is meant for a defensive chasing buy for ADCs, it is quite a negative thing that the build requires so much invenstment into health instead of damage. Furthermore, other defensive options have better builds and, in the end, provide more benefit than Mallet. On the other hand, Ryali's buid path works because it allows a mage to buy a good amount of offensive power while still building towards a defensive purchase. These build problems could be repaired by replacing the Ruby Crystal in the build with a Long Sword.
So, to sum it up, Frozen Mallet's build is less damage oriented and that's generally not a good thing when you're playing a damage-oriented role. Other defensive items (GA, Banshee's) better help damage dealers, you know, deal damage by keeping them in the fight much longer than Mallet's health bonus can.
Now, to talk about the items themselves, because that's kind of the whole point of this rant.
Ryali's gives you a slow on abilities, and a considerable mix of HP and Ability Power. Heck, the item gives enough of these stats for the item to be over 100% efficient, passive or not. Mallet, however, gives a metric assload of health, and a small amount of AD. It doesn't help the cause that the stats are over 350g below being cost efficient. While one may argue that the slow from FM is stronger than the slow from Ryali's (and they would be correct), The stats given from Frozen Mallet are not fitting enough to make up for this. Keep the 90% efficiency if you so please, but giving the item more AD and less health sould be a giant boost to the item's usefulness. And even if the item is made efficient, the slow could be reduced to compensate. As I said previously, changing Ruby Crystal to an AD item could help the item drastically, and changing the item accordingly would make the stats more useful to an AD carry.
The changes I think should occur are similar the the Ryali's adjustment a few patches back: More offense, less HP.
Revised Frozen Mallet (3100g) New build path: Long Sword (360g) + Pickaxe (875g) + Giant's Belt (1000g) + 865g Stats: +450 Health, +50 Attack Damage **Adjusted Passive: Your basic attacks slow your target's Movement Speed by 30% for 1 second (20% slow for ranged attacks). **
The revised stats and cost lets the item be more cost efficient than before, and can easily be tweaked if anything is too powerful (too efficient of stats, too strong of a slow, etc.). The total cost was dropped 300g to make up for the weakened passive, and with the new stats is now about 7% more stat efficient than before (~95%). I believe this can make the item a much more attractive defensive buy to contend with other ADC defensive buys, as an item to react to a fed melee carry or short range damage dealers (Sorry, Brazil).
I know these changes are rough, and the stats were though up off the bat and may need further tweaking, but I think changes in this direction would definitely improve the item beyond being a very situational buy.