Working on a new Assassin card set, need help with the OCG on one of my cards,

[xzero015]

I'm working on a card set called "Cult of Assassins" but i'm having trouble with the lore of this card. (picture will be added later). Any help please?

[img]http://img11.imageshack.us/img11/5572/176266.jpg[/img]

Lore: [i]Activate only when one face-up "Assassin" monster on your side of the field is selected as an attack target. Chose one face-up "Assassin" monster on your side of the field and conduct a battle between it and one monster on your opponents side of the field as if it were your battle phase and it declared the attack. Then if possible continue with the original attack.[/i]

Also, while I'm at it. Can some one jut check over the following sentence from another card I'm doing: [i]When this card declares an attack, at any point before damage calculation, you can activate the following effect:[/i].