Well, the easiest way to explain it is that you keep XYZ summon Monsters Using Constellars Monsters which are amazing for that because They can give you Rank 4,5,6 XYZ Constellars very fast. Also, You can easily keep your hand full of Constellars monsters. I Guess you could also Benefits from all Constellars XYZ Effects, Which Are:
Constellar Omega (Rank 4): Your Constellar Monsters aren't affected by your opponent spell or trap card till the end of either players turn.
Constellar Praesepe (Rank 4): One Constellar monster gains 1000 Attack points, During either player turn, Till the end of that turn.
Constellar Pleiades (Rank 5): Return one card on the field to its controller hand, during either player turn.
Constellar Ptolemy M7 (Rank 6): You can XYZ this Monsters by using any XYZ Constellar Monster you control as the XYZ material. Only during your turn, You can return one monster card from either player field or graveyard to its Owner Hand.-----------------------------------------------------------------
You may be asking "What the hell is umbral have to do in this deck?!" Well, the answer is a simple Trap Card Called "Corrupted Keys" Which Allow you To target An XYZ monster you control and summon Three Umbral Tokens (ATK:??,DEF:00) its attack is the attack of your XYZ Monster. They can't attack your opponent directly.
You can use them to clean your opponent field of Monsters then attack directly with you XYZ Monster. Or you can easily tribute them to summon a high level Monster (Like An Egyptian God monster for example).
This deck also has A variety of spell cards especially for this archetype.
So, I was very, very surprised (and Angry) to notice that no one seems to use this amazing Archetype. With a little tweak here and there I made this deck very powerful.
If anyone have anything to say (Good or bad) about this deck, please write. It will only help me make it much better.