TL;DR Force Staff is the best defensive item for supports to buy, and ranged glass cannon carries make the best use of them.
Force Staff (and Hurricane Pike) is super strong at the moment, for a number of reasons:
They get better the more you have. The enemy can potentially chase after one defensive force. Very few can chase after two forces. Almost no one can chase after three.
Tundra realised this during last TI, which is why both supports almost always went Force Staff.
Now, it is not rare to find teams with 3-4 forces/pikes.
CD is as short as it has ever been. It is now 19 seconds, after getting buffed in both 7.31 (23 -> 20) and 7.32 (20 -> 19). Relatively small buffs true, but enough small buffs make a difference
HP is better than HP regen. In the current meta, 175 hp to let supports survive long enough to get spells off is super important.
For "glass cannon" carries, Hurricane Pike is 500 health (same as Satanic). It's a big reason why now they all seem to have 3-3.5k hp late game.
How does this translate into ranged glass cannon dominance:
It fixes their big weakness in gap close. Traditionally, Lina, Sniper, Drow etc are great sitting at max range hitting, but fold if a Ursa, Monkey King, Spectre etc get up to them. One force staff isn't enough to let them get away.
But if you have 2 forces and a pike, suddenly the ranged carry is 1200 units away and the melee carry can't re-engage easily. Then pike them when they get closer for another 900 units of distance and the melee carry dies before doing anything.
It lets ranged carries outsource their items. If melee carries have a rough game, then they can end up in a spot where they need a bunch of different items to solve problems. Blink to gap close, Skadi to stop lifesteal/kiting, MKB/Daedelus for damage, BKB to survive being in the middle of the enemy. They simply can't do it all at once.
But in a pinch, ranged glass cannons can make their team buy forces and skip buying it themselves. They can focus their gold on buying damage and still be super impactful with a good teamfight execution.
Pike helps a significant amount for their other weakness, low HP. 500 hp is massive. Add on either Satanic or Skadi, suddenly the glass cannons all have 3k hp, which is on par with "tanky" melee cores.
It doesn't help other types of carries nearly as much. It is far harder to coordinate force staffs to gap close your melee carry with their ranged carry than it is to force the ranged carry away.
In addition, this repositioning doesn't really help naturally agile carries (like Stealth Assassin, Phantom Assassin, Spectre, Weaver)
Source: https://www.reddit.com/r/DotA2/comments/11fir4h/force_staffs_strength_is_a_big_factor_in_the/
