The main focus of this thread is the EK capstone, spell critical. The ability to cast a swift spell, in any round you crit on an attack, is very very strong. Now, alot of people seem to think of EK and "Gish" style characters need to be melee. Let's look at the idea, of ranged combat.
Our first option is of course Arcane Archer. But they need to use bows. Bows that have a 19-20 crit range with improved crit. The EK works best with a wide crit range. Our options being crossbows(any), a thrown dagger, or the crystal chakram.
Crossbows, are out because of reload times.
That leaves our other two items. Daggers, which crit at 17-20/x2 with improved critical. And the crystal chakram(CC), which crits at 15-20/x2 with improved critical.
One breaks, the other doesnt. So we'll say we carry both types, daggers for basic enemies, and CC for the stuff that really needs to die now.
Heres the mathy bit to show possible to-hit numbers. Yes it's going to be min-maxed heavily.
Race: Elf
Stats: 20 point buy
Str: 20 (14 base +6 item)
Dex: 36 (19 base + 5 level + 6 item + 2 transmutation + 4 insight)
Con: 12
Int: 16
Wis: 7
Cha: 7
The average CR 20 enemy has about a 39 AC, so thats what we are shooting at as an average enemy to kill.
Important feats: rapid shot, critical focus, improved critical, weapon focus, greater weapon focus
So our attack bonuses are 13 from dex, 4 from greater heroism, 1 from haste, 5 weapon, 2 g.weapon focus
At 20, the basic 2/8/10 fighter/wizard/EK has a Bab 16, so he has a full attack of 16/11/6/1, and with rapid shot 14/14/9/4/-1.
That all gives us 39(95%)<95%>/39(95%)<95%>/34(80%)<95%>/29(50%)<75%> /24(25%)<50%>, with (%)chance to hit and <%> to confirm a critical, which all have the same 30% chance to threat. So about a 69% hit chance, 30% of all attacks will threaten to crit, and of those that threaten to crit, 82% to confirm.
So when fighting a Pit Fiend, over 100 attacks(20 rounds) you will hit him 69 times, threaten to crit him with 30 of those attacks, and confirm 24-25 times. SO that just covers that your on average critting once per round.
Meaning you can unload a full round of combat, and still hit off an offensive spell each round.
SO, keep this concept in mind when you consider the power of the EK. Because there is few things better then raining down +5 bane shattering crystalware with a side of delayed blast fireball.