Arm supports Umbrals

[Toffee.]

Because they have potential.

Umbral Restless
DARK / Level 4
[Fiend/Effect]
Cannot be Special Summoned from the Deck. When this attacking card is destroyed by battle and sent to the Graveyard: You can add to your Hand 2 "Umbral" cards from your Deck, except "Umbral Restless". You can only use the effect of "Umbral Restless" once per turn.
ATK / 0 DEF / 0

Umbral Biter
DARK / Level 4
[Fiend/Effect]
Once per turn: You can make this card's ATK 0, to Target 1 "Umbral" monster with 0 ATK in your Graveyard, and if you do, Special Summon the Target.
ATK / 1900 DEF / 0

Umbral Reaper
DARK / Level 4
[Fiend/Effect]
Once per turn: You can make this card's ATK 0 t Target 1 monster on the field, and if you do, destroy the Target. This effect can only be activated during your Main Phase 1.
ATK / 1700 DEF / 0

Umbral Possession
DARK / Level 4
[Fiend/Effect]
When this attacking card is destroyed by battle and sent to the Graveyard, You can Target the monster that destroyed it: Take control of that Target, it's ATK becomes 0, and it becomes DARK(These effects last until the End Phase). You can only use the effect of "Umbral Possession" once per turn.
ATK / 0 DEF / 0

Umbral Screech
DARK / Level 4
[Fiend/Effect]
You can Send 1 other "Umbral" monster from your Hand to the Graveyard: Special Summon this card(from your Hand). Once per turn: You can Tribute 1 other "Umbral" monster with 0 ATK to make this card's ATK 0, and if you do, Draw 2 cards.
ATK / 1800 DEF / 0

Umbral Minion
DARK / Level 4
[Fiend/Effect]
This card cannot declare a Direct attack. If this card destroys an Opponent's monster as a result of battle: You can make this card's ATK 0, and if you do, add to your Hand 1 "Umbral" monster from your Deck.
ATK / 2000 DEF / 0

Umbral Circle
DARK / Rank 4
[Fiend/Xyz/Effect]
4 Level 4 DARK monsters.
While this card has Xyz Materials, Attack Position "Umbral" monsters with 0 ATK cannot be destroyed as a result of battle. If an "Umbral" monster with 0 ATK battles an Opponent's monster, you can detach 1 Xyz material from this card: Destroy the Opponent's monster as a result of battle at the end of that Damage Step, and Draw 1 card.
ATK / 0 DEF / 0

Umbral Black Heart
Spell
Target 1 "Umbral" monster you control with 0 ATK. Until the End Phase, It's effect(s) are negated(even in the Graveyard) and it's ATK becomes 2100. Then, send 1 "Umbral" monster from your Deck to your Graveyard. You can only activate 1 "Umbral Black Heart" per turn.

Umbral Realm
Spell / Field
Halve all battle damage done to your Life Points from battles involving "Umbral" monsters with 0 ATK. If this card is destroyed by your Opponent's card effect, card while you control an "Umbral" monster with 0 ATK: Add to your Hand 1 "Umbral" card from your Deck, except "Umbral Realm".

Umbral Mind
Spell / Quick-Play
Target 1 "Umbral" monster with 0 ATK. Until the End Phase, that monster cannot be effected by the Opponent's card effects, and cannot be destroyed as a result of battle. Until the End Phase, if that monster's ATK changes, destroy it.

Umbral Soul
Spell / Quick-Play
Tribute 1 "Umbral" monster you control: Gain 2000 Life Points. During the End Phase of this turn, Draw 1 card.

[Your_Innocence]

now that shadow specters has been announced, I'd say it needs a little more level freedom. but as a pre-specters announcement I'd say they are very good

[Toffee.]

Also, to be fair, I made these before Vector played Will-O-Wisp(Level 1 Umbral), so for the most part, the archetype was all Level 4s at the time of this topic's creation.

[玄魔の王]

Doesn't Circle kinda get in the way of Unform plays?