My first attempts (there are a lot...)

[BacksideAttack]

Cytoplasmic Bridge

Continuous Spell

Effect: As long as this card remains face-up on the field, whenever a monster is destroyed, the controller of that card must randomly discard one card from his/her hand.

 

Hundred-Eyes Restrict

*

DARK

Spellcaster/Effect: This card cannot be Normal Summoned or Set. This card can only be Special Summoned by tributing one monster on your side of the field. When this card is Special Summoned successfully, select one monster on the field. This card's ATK and DEF become the ATK and DEF of the selected monster. As long as this card remains face-up on the field, other monsters cannot change their battle positions and their ATK and DEF are decreased by 500.

ATK: ? DEF: ?

 

Thagoren Imperator

******

FIRE

Warrior/Effect: Once per turn, you may discard one card from your hand to look at one card in your opponent's hand and send it to the top of his/her deck.

ATK 2000 DEF 1800

 

Fire Aldhorn

****

FIRE

Beast/Effect: As long as this card remains face-up on your side of the field, your opponent must pay 500 Life Points whenever he/she Normal Summons or Sets a monster.

ATK: 1900 DEF: 1600

 

Water Aldhorn

*****

WATER

Beast/Effect: As long as this card remains face-up on your side of the field, your opponent must pay 1000 Life Points whenever he/she Special Summons a monster.

ATK: 2000 DEF: 1600

 

Omega Aldhorn

********

DARK

Beast/Fusion/Effect: "Fire Aldhorn" + "Water Aldhorn"

When this card is Special Summoned, declare Spell Cards, Trap Cards, or Monster Cards. Then, as long as this card remains face-up on your side of the field, whenever your opponent activates or summons one of the declared cards, he/she must pay 1000 Life Points.

ATK: 2650 DEF: 1950

[Zeppeli Gyro Supreme]

Some OCG errors, and the cards are overpowered, but it's a nice first post.