Yes, there is a limit. I assume your using a sorc here? at 105% FCR, she'll be hitting the 8 frames, or 3.13 casts per second. There's only one more below that, which is 200% FCR, which will give you 7 frames, or 3.57 casts per second.
I have a 200% FCR lightning sorc, her teleport and shooting speed is amazing.
She's the most aggressive/fast sorc i've ever had (30K+ lightning)
A beast in PvM, the best rusher ive had.
She's also very fun in PvP.
I highly recommend a 200% FCR build if you can afford the items. It's worth it.
My build is a 200% FCR + Spirit (shield) + Insight runewords variant.
-It's like a fighter jet plane! aggressive, fast, dangerous :clap:
-Very high damage
-Ultra high teleport speed at a very low mana cost.
-A beast in PvM, can destroy thousands of monsters in a few minutes.
-great fun in PvP. Against players who don't absorb, it's usually one shot-one kill. I'm not an expert though, i don't pvp very often.
-No max block, no energy shield, thus weak sorc.
(not really a problem for me because my merc is really strong and my teleport speed keeps me away from danger)
-Very bad magic find %: i don't care about mf %, i prefer to have a very high killing speed. Imo, faster kills=faster drops=faster mf
The core of this build is the Insight runeword for your merc. Lightning has a very very high mana drain at 200%FCR, chain lightning is even worse!
You can try all the +mana per kill items you want (silks boots, rare rings etc.), you just can't help it.
It's like trying to refuel a fighter jet plane with a small 10 liter gasoline tank ...
The mana cost is just insane.
So i made an insight runeword (Ral Tir Tal Sol) for my act2 hell defensive merc. (I'm too lazy to level them from normal)
The meditation aura will allow you to spam your spells in all directions. It gives the build much more freedom of action.
Btw, my merc is wearing Enigma. I know people usually say "what the hell? are you stupid?" but i had that enigma laying around and it made my merc quite strong.
Items : This is an expensive sorc, it's not recommended for begginers.
With cheap items this sorc is really weak. It only shines with the best items.
-Shield: Spirit 35%FCR in sup 15%ED monarch. (sexy, powerful and cheap runeword!)
-Weapon: Hoto (can't go wrong with +3 skills, 40%FCR and up to 40 all res)
alternative: good Eschuta for added dmg of course, but i like hoto for the high res
-Helm: Griffon ( 25% FCR, -%/+% to lightning dmg, +1 skils, awesome!)
socketed with a lightning facet
-Belt: Arachnid (+1, 20% FCR)
-Armor: Upgraded perfect Viper 35 socketed with a lightning facet.
-Amulet: i'm using a crafted amu:
+2 lightning, 10%FCR, regenerate mana 8%, all res +16, +23% MF
Yep these are very rare and expensive.
-Rings: 2 sexy rare rings with 10%FCR and some very nice res
-Gloves: Magefist upgraded two times (warning high str req), or TO gloves for the 20%FCR
-Boots: you decide (I'm using silks for a little more mana)
Weapon switch: +3 to a cold armor orb / spirit shield
alternative: CTA + spirit
Annihilus with good stats (because the monarch has a high str req)
As much lightning skillers as you can wear. (lifers if you are filthy rich)
-Enough strength for items (e.g. monarch shield...)
-No dex (monarch block rate is too low imo)
-No energy (you don't need any with insight)
-Vita: all the rest
It's quite simple.
Pure lightning/chain lightning fully synergised build.
1 point in thunder storm just for fun and a little more dmg.
Energy shield: you decide (i don't like it much)