with this method you can virtually secure victory by targeting a Number 86: Heroic Champion - Rhongomyniad in your graveyard and utilize all of its effects (without Rhongomniad's drawback of detaching materials since Barian Hope's effect ends before Rhongomniad's cost must be paid), making Barian Hope a 6500 (Potentially 7500) beatstick unaffected by card effects, cannot be destroyed by battle, preventing your opponent from summoning, and once per turn you can clear the opponents field.
After using the effect of "Number C102: Archfiend Seraph" (making an opponent's monster's ATK become 0), Xyz Summon this card using that monster, then equip "Stoic Challenge" to it. Assuming your opponent has no answers, and that "Number C102" had 3 Xyz Materials, this card will inflict 12,800 damage to your opponent.
Use this card's effect to target a "Number C101: Silent Honor DARK" in your Graveyard, use the copied effect to attach an opponent's monster to it as Xyz Material, then, as this card is now a "Number C10X" monster, Xyz Summon a second copy of this card on top of itself, resulting in a 2000-point ATK boost while also removing an opponent's monster.
Use cards like "Xyz Energy" or "Xyz Gift" to get "Number" monsters attached to it into the Graveyard, while using cards like "Overlay Regen" to keep its ATK high.
You can also have this card copy the effects of "Number" in order to help with the Detaching of "Number" attached as Xyz Material (by activating the copied effect), or attaching of cards (through monsters such as Number C101, Number C9, Number 79 , etc.) to keep the ATK High.
Incredibly, it is possible to Xyz Summon this card with 6000 ATK using just 2 cards (and an empty field and Graveyard):
Have "Rank-Up-Magic Argent Chaos Force" in your hand and "Rank-Up-Magic - The Seventh One" on top of your Deck. Draw "The Seventh One" and activate it, Xyz Summoning "Number C107: Neo Galaxy-Eyes Tachyon Dragon" (1 Xyz Material). Xyz Summon "Galaxy-Eyes Full Armor Photon Dragon" through its own effect using "Neo Tachyon" as Xyz Material (2 Materials). Activate "Argent Chaos Force", Xyz Summoning a second "Neo Tachyon" using "Full Armor" as Xyz Material (3 Materials). Xyz Summon a second "Full Armor" using "Neo Tachyon" as Xyz Material (4 Materials). In response to this, activate "Argent Chaos Force's" effect from the Graveyard to return it to the hand. Use "Argent Chaos Force" to Xyz Summon a third "Neo Tachyon" using "Full Armor" as Xyz Material (5 Materials). Finally, Xyz Summon this card using "Neo Tachyon" as Xyz Material (6 Materials).
"Skill Drain" will cripple this card, dropping its ATK to 0 and negating any effects it has gained.
Effects that return monsters to the hand like "Penguin Soldier" will get rid of this card.