Shadowbinder

[Lunar Origins]

Shadowbinder

Level 1 // DARK

[ Fiend // Tuner // Effect ]

When this card declares an attack:  Target 1 monster on the field:  This card gains that monster's ATK and DEF.  If this card destroys a monster by battle:  You can have all "Shadowbinder" monsters you control gain that monster's effects until they leave the field.

[ ATK: 0 // DEF: 0 ]

 

Ugh.  Wording.

[Major's Shadow]

The way you make the wording sound, it's almost like shadowbinder will become its own archetype (since you put the clause "monsters" after its name). Its effect could be pretty nutty, taking effects from on-board monsters pernamently. Not to mention, the effects would stack, so keeping track of multiple shadowbinders, with multiple stacked effects, would be a nightmare. It's perfectly fine if the monster that attacked kept the effects, wouldn't be too overkill considering a lot of the effects are either archetype exclusive, on-summon, or you don't have the legal means of activating it. Honestly, this sounds more like a Hearthstone card rather than a YuGiOh card. Can't see any practical applications beyond the ATK buffing and it being a Level 1 Tuner. Also, just some reccomended OCG changes to make everything more clear:

[spoiler=OCG Corrections]

Original: When this card declares an attack:  Target 1 monster on the field:  This card gains that monster's ATK and DEF.  If this card destroys a monster by battle:  You can have all "Shadowbinder" monsters you control gain that monster's effects until they leave the field.

New: If this card declares an attack: target 1 other monster on the field; this card gains that monster's current ATK and DEF. If this card destroys an opponent's monster by battle: You can have all "Shadowbinder" monsters you currently control gain the effect(s) of that destroyed monster (not too sure on the wording w/ this one).