Strange, I'll see if I can test it out on the PC when I get time on my hands.. I'll keep you posted :)

Alright after setting aside a bit of time I was able to tested it. In order to stack you just need 2 different types of potion with different effect description (ie. different magnitude or an additional effect, it doesn't matter which).

Using only generic potions the max you'll get is 90%, stacking anymore will diminish the effect due to the multiplicative %. [Max stack 2: Initial (Elixir), 1st stack (Philter), 2nd stack, (Elixir)]

Using custom potions made with Alchemy at 100 and with the entire tree perked, you're potions will peak at 149% (game rounds it up to 150% during calculations) anymore will diminish the effect due to the multiplicative %. With additional alchemy gear, you should be able to stack more and your effects be even stronger. [Max stack 8: ...]

In regards to destruction, using both generic and custom potion I was veritably unable to replicate the stacking potion stacking principle. I also had a volunteer test it on her PS3 for me and likewise she was unable to replicate it using the following above.

I'm thinking of starting this build tomorrow.  Been playing as a Sorcerer which, although I do love, is at level 37 and now has 2 synergized silver swords and the twin souls perk, and is becoming a bit easy.   I also really miss beheadings, which I see the Sentinel has.  One question though, why no Impact perk?  I assume because it's kind of cheap and repetitive, but I usually take it when I take dual cast in destruction, and I'm thinking with 100% stunted magicka it might be nicely balanced since you wouldn't be able to spam it all that much right?  Just wondering if there was a roleplay reason or something.  Anyway, really enjoying your builds so far, that Kingslayer looks interesting as well...

I love the look of this build, but I am wondering about the armor.

Am I understanding right that the enchanted armor you have listed is store bought? So you'll have to wander around towns, waiting for inventories to refresh to find the right pieces, correct? So any enchanting you do is just done without perks to give you little boosts till you find the listed pieces?

Also, about using alchemy to boost the atronach stone, can you only do that once? Meaning you should get alchemy leveled and perked before you use the stone?

All the enchanted armour is shop bought, just save, kill the owner and reload til you get the pieces you want. You obviously need to be level 38 to get all the pieces though.
No you can swap the stone for another, then drink your potions then get the Atronach stone again.

Thanks for the clarification! My new sentinel is lvl 9 now, with a perk or two in all of the above listed trees, but now I'm going to concentrate on getting smithing up and get into that sweet robot armor. :D

Thanks Mason, makes perfect sense. I wasn't thinking like a person with stunted magicka. I'm level 7 I think and haven't gotten the atronach stone yet, I hit Embershard Mine for some iron and went to Arcadia's as well, leveling up my smithing and alchemy a bit, but I think it's now time to go get that stone before I hit Bleak Falls Barrow. As someone who has never leveled alchemy before, I was psyched when I found a steel helm of alchemy in the mine--clearly this character was destined to become a sentinel. This playthrough will definitely be a new and unique experience for me, with both alchemy and the advanced atronach stone, I only wish I had tried it sooner.