How long does the boosting ATK effect last?

Found some fanart of the final boss from Ultraman R/B, eh? Actually looks really appropriate for a YGO card.

Here, let me clean up the text a bit.

Once per turn: You can send the top card of your deck to the GY and increase this card's ATK by the number of LIGHT monsters in your GY x 200. When this card destroys an opponent's monster by battle: Equip it to this card. Once per turn: You can send 1 monster equipped to this card to the GY to target 1 card your opponent controls; destroy that target.

If you want to be able to use the "chuck an absorbed monster at something" effect under conditions such as Macro Cosmos, I suggest using this instead.

Once per turn: You can target 1 card your opponent controls; destroy 1 monster equipped to this card, then destroy that target.

If you want the destruction of the equipped card and the target to happen simultaneously, replace "then" with "and" or "and if you do", depending on if you want the two actions to depend on each other or if you only want the second to depend on the first.

7912469
Damn, I did forget about that, the end of the turn

7912471
Thanks, I'm also putting it in that the effects are a HOPT, and I'm thinking of making it a Synchro or an Xyz monster

7912473

Okey-doke. Do you want to make ALL of the effects HOPT? I kinda feel like the equip effect should be left as is in case this card is given multiple attacks.

Once per turn: You can send the top card of your Deck to the GY, and if you do, increase this card's ATK by the number of LIGHT monsters in your GY x 200 until the end of the turn. When this card destroys an opponent's monster by battle: Equip it to this card. Once per turn: You can send 1 monster equipped to this card to the GY to target 1 card your opponent controls; destroy that target. You can only use each effect of "Hyper Core Dragon" once per turn.

If you wanna leave the equip effect alone, maybe this would work.

When this card destroys an opponent's monster by battle: Equip it to this card. You can only use each of the following effects of "Hyper Core Dragon" once per turn.

• During your Main Phase: You can send the top card of your Deck to the GY, and if you do, increase this card's ATK by the number of LIGHT monsters in your GY x 200 until the end of the turn.
• You can send 1 monster equipped to this card to the GY to target 1 card your opponent controls; destroy that target.

But I'm just making suggestions here. This is your card, you get final say over how it works.

7912807
I didn't have any plans to change it, and other than some different spacing and lines, I don't see much difference between the two text examples. BTW, does this monster look more like a Predaplant or a Naturia monster?

7912808
The difference is that the hard once-per-turn only applies to those two effects rather than all three.

I'd say that's a Predaplant monster, definitely. Naturias tend to have a cuter appearance, while the bigger ones have the appearance of guardians.