Reposting this here. Original credit to Beimeith.
Ethereal Weave RK. III
Cast Spell: Ethereal Incandescence Rk. III
35% Chance to trigger: Ethereal Weave Chance III
Ethereal Weave Chance III
Cast Spell: Ethereal Weave Acquittal III
32% Chance to trigger: Ethereal Hoarfrost Rk. III
32% Chance to trigger: Ethereal Salvo Rk. III
32% Chance to trigger: Ethereal Incandescence Rk. III
Ethereal Weave Acquittal III
Reduce Mana by 5567
Basically:
1) When you cast Ethereal Weave, you cast Ethereal Incandescence, AND 35% chance to proc Ethereal Weave Chance.
2) IF you proc Ethereal Weave Chance, you cast Ethereal Weave Acquittal, AND 96% chance to proc ONE of the three Ethereals, (32% Chance for each one * 3 = 96%).
3) IF you cast Ethereal Weave Acquittal, you lose 5567 mana.
End Result:
Spell Procs:
65% Chance to proc NO extra Ethereal spell AND spend 4,948 mana
4% Chance to proc NO extra Ethereal Spell AND spend 10,515 mana
31% Chance to proc ONE extra Ethereal spell AND spend 10,516 mana
Note on Mana Cost:
Weave Cost - Normal Ethereal Incandescence Cost = 450 wasted mana.
Weave Cost - Normal Ethereal Incandescence Cost + Weave Acquittal Mana Cost = 6017 wasted mana.
Weave Cost - Normal Ethereal Incandescence Cost + Weave Acquittal Mana Cost - Average Cost of the three Ethereals = 1721 wasted mana.
With Twincast:
Spell Procs:
42.25% Chance to proc NO extra Ethereal spells AND spend 4,948 mana
5.2% Chance to proc NO extra Ethereal spells AND spend 10,515 mana
0.16% Chance to proc NO extra Ethereal spells AND spend 16,082 mana
40.3% Chance to proc ONE extra Ethereal spell AND spend 10,515 mana
2.28% Chance to proc ONE extra Ethereal spell AND spend 16,082 mana
9.61% Chance to proc TWO extra Ethereal spells AND spend 16,082 mana