When you use honest's effect, does the selected monster's attack become the same as the opponent's or does the opponent's attack get tacked on to what you already have?

YOUR monster will get all the atk of your OPPonent monster.
For example: Player A has sabesaurus (atk 1900) and attacks player B Thunder king monster(atk 1900)
Player B uses honest in damage step... now Thunder gets the 1900 atk of sabesaurus (1900 + 1900 = 3800)
and sabesaurus is destroyed n player A loses 1900 damage (3800 - 1900 = 1900 to player A)

Hope this answered ur question

omg read the card. Your monster gain atk equal to your opp monster.

Exaple:
U attack with 1400 and your opp monster has 1600 ATk. U activate honest eff and your monster become 3000 ATK.

Thank you I'm just making sure. I was playing on DN today, and I thought that's what the effect implied. I used it on one of my monsters and my opponent said that both monsters were the same atk and the were both destroyed. He left the duel out of rage and I just wanted to make sure I got my effect right.