AUTO 【V】: Limit Break 4 (This ability is active if you have four or more damage): [Choose 1 <<Angel Feather>> from your hand and put it into your damage zone] When this unit attacks a vanguard, you may pay the cost. If you do, choose 1 card from your damage zone, and add it to your hand.
AUTO 【V】: When a card is put into your damage zone, this unit gets POWER +2000 until end of turn.
At first, I didn't give this much thought - it's clearly a good card. Just how good, though, never really hit me until I gained some experience in having to ride The Phoenix, Calamity Flame. I'll have you know that despite being your "worst option", you're not going to die any time soon just because you rode it. Why? It's naturally resilient to harm, gaining power each time it's hit. Shamsiel not only shares that bulk, but she also possesses another sweet ability that really ties the deck's battle plan together.
Your best rear-guards used to be somewhat awkward and clunky; they demanded plays from these supporters every turn, lest they end up being decidedly average. You had at most 12 chances to pump your columns, only if the support came up, and only if your field setup allowed them to be played. No longer! Shamsiel, as long as you have 4 or more damage, will do the job for you every single turn, for no investment whatsoever! That being the case, the need for cards such as Love Machine Gun and Happy Bell is drastically lessened. Taking matters further, all 3 of your columns can now attack at full force, backed by 8 criticals. Delicious.
AUTO: [Choose an <<Angel Feather>> from your hand, and put it into your damage zone] When this unit is placed on Guardian Circle, if you have an <<Angel Feather>> vanguard, you may pay the cost. If you do, choose a card from your damage zone, and put it into your hand.
This little number just got a lot more effective. Who doesn't want defense on par with Booster 5's megabosses?
AUTO: When you Ride this Unit with another <<Angel Feather>>, you can call it to a Rearguard Circle.
CONT 【R】: If you have an <<Angel Feather>> Vanguard, this Unit gains: "ACT 【R】: [Counterblast 1, Place this Card in Soul, and Choose 1 <<Angel Feather>> in your Hand, and place it in your Damage Zone] Choose 1 card in your Damage Zone, and add it to your hand.
And how about this new starting Vanguard? Going -1 never felt so good!
AUTO: [Counterblast (1)] When this unit is placed onto a vanguard or rear-guard circle, if you have an <<Angel Feather>> vanguard, you may pay the cost. If you do, place the top card of your deck into your damage zone, then when this turn's end phase begins, choose one card in your damage zone. Return it to your deck, then shuffle your deck.
This card and its grade 1 equivalent are also options should they strike your fancy. As far as I'm concerned, though, the grade 1 slots are spoken for. Heck, most of the deck is!
Grade 0 (17)
1 New Starter
4 Sunny Smile Angel
4 Critical Hit Angel
4 Rocket Dash Unicorn
4 Bouquet Toss Messenger
Grade 1 (15)
4 Burst Shot, Bethnael
4 Thousand Ray Pegasus
4 Pure Keeper, Requiel
3 Battle Cupid, Nociel
Grade 2 (10)
4 Core Memory, Armaros
4 Million Ray Pegasus
2 Love Machine Gun, Nociel/Doctoroid Megaros
Grade 3 (8)
4 Chief Nurse, Shamsiel
2 Circular Saw, Kiriel
2 The Phoenix, Calamity Flame
Angel Feather, coming soon to a meta near you!