Gonzar, The Black Demon's King

[Mastee157]

This is part of a deck that I am making..

This card can't be Special Summoned. This card must be Synchro Summoned by a "Demon Gate Keeper" and a "Major Demon". You can toggle/untoggle the ability:"Every "Black" Creature except Gonzar, The Black Demon's King gets 500+/500+. To attack, Gonzar must disablet this effect.

 

[BatMed]

to be honest,, your OCG is the worst -_- ,, I didn't understand the card's effect

try this website, it maybe will fix your OCG and make it better

http://yugioh.wikia.com/wiki/Problem-Solving_Card_Text

[Big Lez]

The monster-type you mean is called Fiend

Is black creature some kind of archetype?

 

I think what this card does is being Synchro Summoned (with somehow Fusion Summoning Like Conditions) 

And disable/enable its effect whenever he wants. The effect could be either that he increases the ATK/DEF of other "Black" monsters you control, or that he increases his ATK/DEF for every "Black" monster you control by that amount. And to attack he needs to disable its effect

Am i right so far?

There is a lot of things on this card i  dont like.  BUT

Since youre new to this i wont actually rate - i only try to help you out

 

Start with Common Cards - for some reason every new Member (myself included - a couple of years ago ) starts with ULTIMATE SUPER monsters. Begin with simple effects and simple cards. This helps you improving OCG, Balancing and you'll become more and more creative before you realize it 

 

I know - Black Demon Kings and Ultimate Dragon Lords might be more fun to create for many people, but trust me. The Level 4 monsters, the simple Traps & Spells...they all are actually more fun and more interesting for anyone who likes that game 

 

Best wishes for your next try ;)