The Necromaniac (Xyz Monster)

[Zazubat]

After reading up on Damage Step, I found out that cards that change ATK/DEF can't be activated during Damage Calculation, unless specificly said that they can, so that means I could abuse this fact, not something that's ever going to happen, but now that I know I can design cards like this that's a little bit better because of that effect. Anyways here's the card:

 
2 Level 4 monsterrs
This card gains 200 ATK and DEF for each Xyz Material attached to this card. Once per turn, if this card battles, during Damage Calculation: You can detach 1 Xyz Material from this card; shuffle your opponent's monster into their Deck, and if you do, they can Special Summon 1 monster from their Deck with a different name whose ATK or DEF is equal to or lower than the ATK or DEF of the shuffled monster. When this card with Xyz Materials is destroyed by battle, at the end of the Damage Step: Shuffle your opponent's monster into their Deck, then your opponent can Special Summon 1 monster from their hand or Graveyard whose ATK or DEF is equal to or lower than the ATK or DEF of the shuffled monster.

[Darkneptune]

the cards effect is quite nice, and original. about the text, you could write it as "the monster this card battles". Legendary jujitsu master has a similar wording , you could check it for reference. the art is quite good for the cards theme. overall id say 8/10

[Aix]

First things first, it has too much ATK. Even Gem-Knight Pearl has less ATK. The effect is quite OPed as well, you can get rid of any boss this way and they most likely wouldn't have anything with exactly equal ATK or DEF. I would suggest letting them Special Summon from the Deck so they actually get to Special Summon. So with the fixes I suggest and OCG fixes it would be:

 

The Necromaniac

[DARK/Rank 4/Spellcaster/Xyz/Effect]

2 Level 4 monsters

This card gains 200 ATK and DEF for each Xyz Material attached to it. Once per turn, if this card battles, during damage calculation: You can detach 1 Xyz Material from this card; shuffle your opponent's monster into their Deck, and if you do, they can Special Summon 1 monster from their Deck with a different name whose ATK or DEF is equal to or lower than the ATK or DEF of the shuffled monster. When this card with Xyz Materials is destroyed by battle, at the end of the Damage Step: Shuffle your opponent's monster into their Deck, then your opponent can Special Summon 1 monster from their hand or Graveyard whose ATK or DEF is equal to or lower than the ATK or DEF of the shuffled monster.

ATK/ 1900 DEF/ 700

 

That is just a sample suggestion. It should go something along the lines of this.

[Zazubat]

I actually like your effect, it balances it out a bit more, so I'll use that. Though your first wording is wrong, I copied my wording from an actual card Xyz Monster so it should be right, but that's okay.

[Darkneptune]

i think the attack was ok the way it was. gem knight pearl has 2600, this guy has 2500 when summoned, and lowers each time he uses his effect. but again, thats just my thoughts.