Arcane spell failure and Eldritch Blast

[Redclaw1992]

Hi everybody, I've got a tank build in mind, fvs 12 fgt 5 wlk 3, using acolyte and making use of the pact attunement feats to get the eldritch Blast/pact damage, t5 stalwart defender and healing capabilities from FVS.
My only problem is dealing with the arcane spell failure, which from what some people said to me would have made my eldritch Blast fail. Is that the case? I was testing around and apparently, even if I see the check rolling, the blast works every time in cone shape. Need some insight.

[slarden]

I just did some testing and I am getting arcane spell failure:

(Combat): You roll to see if your Eldritch Chain fails because of your bulky equipment. You roll a 15 : arcane spell failure!

The animation doesn't look any different, but there is no damage according to my combat log.

[rimble]

The animation doesn't look any different, but there is no damage according to my combat log.

Just confirmed this with Cone. Looks like you're blasting, but no damage registers when you fail your ASF check.

[h46av8r]

Is this a bug or WAI? I'd assume the former? Warlocks should be able to cast warlock spells without ASF even if you're picking up additional blast dice via the feats assuming your in light armor no shield? (Or medium if went up the ES tree.) Per the wiki "The Arcane Spell Failure from light armor (but not shields) is ignored by Warlocks when casting Warlock spells. The Enlightened Spirit Tier IV enhancement extends this benefit to medium armor.". Or am I misunderstanding the question?