L33T is forbidden in YGO? Who told you that?

R41D 5H4D0W 1363ND5
Continuous Trap
While you control a "R41D" monster, the first opponent's Normal Spell Card effect to resolve becomes "Your opponent discards 1 card". If you control a "R41D" monster: You can send this face-up card from the field to the GY, then target 1 card your opponent controls; destroy it. You can only use this effect of "R41D 5H4D0W 1363ND5" once per turn.

R41D H4CK3R
Level 4 DARK Cyberse/Effect
1500/1500
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent draws 1 card". You can Tribute this card; add 1 "R41D" Dark Tuner from your Deck to your hand. You can only use each effect of "R41D H4CK3R" once per turn.

R41D 1NV4D3R
Level 8 DARK Cyberse/Dark Tuner/Effect
1600/1600
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent Special Summons 1 Level 4 or lower "R41D" monster from their Deck". During your opponent's turn (Quick Effect): You can pay 1000 LP; immediately after this effect resolves, Dark Synchro Summon 1 "R41D" Dark Synchro Monster using monsters you control as material. You can only use each effect of "R41D 1NV4D3R" once per turn.

R41D 1N7RUD3R
Level 4 DARK Cyberse/Effect
1700/1200
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent adds 1 "R41D" Spell/Trap from their Deck to their hand". If this card is sent to the GY as Dark Synchro Material: You can discard 1 "R41D" monster, and if you do, draw 2 cards. You can only use each effect of "R41D 1N7RUD3R" once per turn.

R41D H4MM3R3R
Level 8 DARK Cyberse/Dark Tuner/Effect
1900/1900
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent Special Summons 1 Level 4 or lower "R41D" monster from their GY". During your opponent's turn (Quick Effect): You can pay 1000 LP; immediately after this effect resolves, Dark Synchro Summon 1 "R41D" Dark Synchro Monster using monsters you control as material. You can only use each effect of "R41D H4MM3R3R" once per turn.

R41D 5M45H3R
Level -4 DARK Cyberse/Dark Synchro/Effect
2500/1500
1+ non-Dark Tuner monsters - 1 Cyberse Dark Tuner
Once per turn, when an opponent's monster activates its effect (Quick Effect): You can pay 1000 LP; the activated effect becomes "destroy 1 monster on each player's field". If this card in your possession is sent to the GY by an opponent's card: You can Special Summon 1 "R41D" monster from your Deck. You can only use this effect of "R41D 5M45H3R" once per turn.

R41D 614N7
Level -4 DARK Cyberse/Dark Synchro/Effect
2400/1500
1+ non-Dark Tuner monsters - 1 Cyberse Dark Tuner
Once per turn, when an opponent's monster activates its effect (Quick Effect): You can pay 1000 LP; the activated effect becomes "this card loses 1000 ATK". When this card destroys an opponent's monster by battle: You can inflict damage to your opponent equal to that monster's original ATK.

R41D D3M0N
Level -12 DARK Cyberse/Dark Synchro/Effect
3000/3000
1+ non-Dark Tuner Cyberse monsters - 1 Cyberse Dark Tuner
Once per turn, when an opponent's monster activates its effect (Quick Effect): You can pay 1000 LP; the activated effect becomes "destroy all other cards you control". Banish any monster destroyed by battle with this card. Once per turn, during your opponent's End Phase: You can target 1 face-up monster your opponent controls that did not activate its effects this turn; destroy it.

R41D R3X
Level 4 DARK Cyberse/Effect
2000/0
Cannot be Normal Summoned/Set. Must be Special Summoned by its own effect. When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent adds 1 "R41D" monster from their Deck to their hand". You can only control 1 "R41D R3X".

R41D W4ND3R3R
Level 8 DARK Cyberse/Dark Tuner/Effect
1200/2800
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent gains 1000 LP". During your opponent's turn (Quick Effect): You can pay 1000 LP; immediately after this effect resolves, Dark Synchro Summon 1 "R41D" Dark Synchro Monster using monsters you control as material. You can only use each effect of "R41D W4ND3R3R" once per turn.

R41D D357R0Y3R
Level -4 DARK Cyberse/Dark Synchro/Effect
1800/2000
1+ non-Dark Tuner monsters - 1 Cyberse Dark Tuner
Once per turn, when an opponent's monster activates its effect (Quick Effect): You can pay 1000 LP; the activated effect becomes "1 face-up monster your opponent controls gains 1000 ATK". When this card destroys an opponent's monster by battle: You can destroy 1 card in your opponent's hand (at random) or their field.

R41D N3CR0M4NC3R
Level 4 DARK Cyberse/Effect
1500/1500
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent Special Summons 1 Cyberse monster from their hand or either GY to their field". If this card is Normal or Special Summoned: You can Special Summon 1 Cyberse Dark Tuner from your hand in Defense Position. You can only use each effect of "R41D N3CR0M4NC3R" once per turn.

R41D FR0N713R
Field Spell
All "R41D" monsters on the field gain 400 ATK/DEF. Once per turn, during the End Phase: You can target 1 face-up monster your opponent controls that did not activate its effects this turn; destroy it, and if you do, inflict 800 damage to your opponent.

R41D 8R34K
Continuous Trap
While you control a "R41D" monster, the first opponent's Normal Trap Card effect to resolve becomes "Your opponent Special Summons 1 "R41D" monster from their GY". If you control a "R41D" monster: You can send this face-up card from the field to the GY, then target 1 card in your opponent's GY; banish it. You can only use this effect of "R41D 8R34K" once per turn.

R41D D14810
Level 4 FIRE Cyberse/Effect
1800/800
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "you take 500 damage". If this card is sent to the GY as Dark Synchro Material: You can add 1 "R41D" card from your Deck to your hand, except "R41D D14810". You can only use each effect of "R41D D14810" once per turn.

R41D DR460N
Level -12 DARK Cyberse/Dark Synchro/Effect
3000/2500
1+ non-Dark Tuner Cyberse monsters - 1 Cyberse Dark Tuner
Once per turn, when an opponent's monster activates its effect (Quick Effect): You can pay 1000 LP; the activated effect becomes "destroy all Spells and Traps on the field, then this card's ATK becomes 0". Once per turn, during your opponent's End Phase: You can target 1 face-up monster your opponent controls that did not activate its effects this turn; destroy it.

R41D 4V3N63R
Level 4 DARK Cyberse/Effect
1200/1200
When an opponent's monster activates its effect (Quick Effect): You can Special Summon this card from your hand, and if you do, the activated effect becomes "your opponent's monsters cannot be destroyed by battle this turn". While this card is in your GY, if a face-up "R41D" Dark Synchro Monster you control is destroyed by battle, or leaves the field because of an opponent's card effect: You can Special Summon this card. You can only use each effect of "R41D 4V3N63R" once per turn.

R41D R3V3N63
Normal Trap
Tribute 1 Cyberse monster, then target 2 cards on the field; destroy them, and if you do, you can add 1 "R41D" Spell/Trap from your Deck to your hand, except "R41D R3V3N63". You can only activate 1 "R41D R3V3N63" per turn.

3V11 R41D
Continuous Spell
While you control a "R41D" monster, the first opponent's Normal Spell Card effect to resolve becomes "Your opponent Special Summons 1 "R41D" monster from their GY". If you control a "R41D" monster: You can send this face-up card from the field to the GY; draw 1 card. You can only use this effect of "3V11 R41D" once per turn.

R41D W4RF4R3
Continuous Spell
While you control a "R41D" monster, the first opponent's Normal Trap Card effect to resolve becomes "Your opponent Special Summons 1 "R41D" monster from their Deck". If you control a "R41D" monster: You can send this face-up card from the field to the GY; Special Summon 1 "R41D" Dark Synchro Monster from your GY. You can only use this effect of "R41D W4RF4R3" once per turn.

R41D M155113
Equip Spell
Equip only to a "R41D" monster. It gains 300 ATK. While equipped to a Dark Synchro Monster, it gains 600 ATK instead. Negate the effects of a monster destroyed by battle with the equipped monster (including in the GY).

R41D 70RP3D0
Normal Trap
Target 1 Level 4 or lower "R41D" monster in your GY; Special Summon it. If a Cyberse monster(s) you control would be destroyed by battle or card effect, you can banish this card from your GY instead.