Legend:
HP = Health Points/pool -- PA = Physical armor -- AH = Ability Haste -- MP = Magic power -- min = minimum MA = Magic armor
-- s = Seconds -- Ult = Ultimate (R Ability) -- TNC = Tenacity -- STR = Strength -- CD = cooldown -- lvl = Level -- MR = Mana Regeneration -- Mpen = Magic Penetration -- CDr = Cooldown reduction

All info below is subject to change, and is only static to the day of upload (1/9/24)

This is for max shields, but minimal card utility. To provide burst and engagement protection

Crest

The Crest is tricky, and obviously depends on a lot of factors. "Tranquility" is actually tangible due to the huge amount of MP you'll be building, or the tried and true "Reclamation" to pair with your escapes (and teams) since we're going spike shielding with this build.

Core Items

1.
With some debate, when it comes to core stats (while not proc'd) the best top shield value "support" card (per cost) is "Wellspring". Running Muriel, it's expected to be poking the other team, so this will also proc "Soothing Waters" passive for faster "Vital Waters" procs. With 45 MP, 20% H&S, combined with "Vital Waters" you will be healing at a minimum ((45*.1)+20)+20% = (49.5+20)+20% = 59.4/2 = 29.7/s for 2 seconds every 20 seconds*. This will also provide (100+(45MP.5))+20%H&S or ~147 shield value (at lvl 1 shield). Keep in mind you will be poking, while restoring HP, so we should average ~10 CDr for the "Vital Waters" proc.
Note Wellspring is rank 18/26 of available MP cards @0.01 base shield value per gold.

2.
Next we build into "Timewarp". Relatively expensive, but cheap build cards to give MR. This is a great card to build for shield strenth and ability CD because it's also the only high MP card that also gives MR. It's passive "Chime" synergizes great with "Vital Waters" as there's multiple passives that reduce CD and trigger your shields and heal trickles.
Note Timewarp has a .0140625 base shield value per gold.

3.
At this point we may be a pinch behind on average value, so we'll want to spike up a bit. And so we'll use the 2/26 value card. "Golems Gift" The reason this card is valued so highly, is because of the pure stat value per cost. For only 2900 gold, you get a -minimum- of 70 MP, and a passive of 100 MP with your stacks from "Stoneweaver". Not to mention you're gaining a little haste for CDr, and burst medigation via "Stone Skin"
Note Golems Gift has a .017241379 base shield value per gold.

4.
We're looking to maintaining the highest value we can, with the least lost stats in MP cards, and from here we have, what I consider to be an unsung hero in this regard. "Spirit of Amir". Not counting the -passive- 8% MP bonus for being in lane, it has a respectable 75MP -and- 15AH. Between those facts you're also obtaining a passive 3% speed bonus, all for 2900 gold. If you start to get dry on mana, this beast of a card also provides 2% mana per enemy unit (20% if you KS ;) )
Note Spirit of Amir has a .012931034 base shield value per gold

We scale boys.

5.
There's not a ton of matches that allow you to get suppy full build, but if we make it here: "Oblivion Crown". This card, by a relatively large margin, has the absolute best base shield value per gold @.019166667 -not- counting the 15% bonus MP (that yes, does scale with "Spirit of Amir" 8%).

Flex

If you notice you're lacking on anti-heal in a lane, "Tainted Scepter" is 12/26 in value. I will say that while "Tainted Totem" is hotdog water in an open cup for value sitting at 23/26, it's passive is great when ulting in from afar.

End Game

"Wellspring" is great, but if you're looking to maintain spike shields for getting jumped, or to help initiate engagements, you may consider swapping "Wellspring" out for "Wraith Leggings". It seems odd, but between your CDr, and lack of defense with this build, the speed boost can really come in handy, and your abilitys won't tickle much anymore either as this card also provides Mpen and bonus damage to enemies below 40% HP by 15%

Stay Salty