Macro question

Hi all, I was wondering if someone may be able to answer a Macro question. I play a version of an old game called Bushido and use a macro I wrote for the D20 to hit roll in the game. In Bushido, you basically take the Skill of the character 19 or less plus their level bonus and other bonuses to come up with a positive # than you subtract the AC.  Example: A guy with a sword skill of 15 that is level 2 and has a 1 bonus for his good weapon would have an 18 minus the AC of the enemy to hit. You need low on the d20 in Bushido. This is not a problem ... here is my macro. /me Attack @{Weapon_1} was by [[@{Raw_BCS_1}+@{level}+@{Quality_1}+@{Special_Hit_Mod_1}-?{Armor Class|0}+?{Situational Modifer|0} -1d20]]  The macro looks on my character sheets and pulls the skill from the Raw BCS adds the level from that attribute, then other modifiers as I mention above. ***The problem is in Bushido is this. In Bushido, you have some attacks that are half the calculated number.  So for example: if after all modifiers the attacker would have a 9 to hit ... they would need a 4 or less to hit.(Rounds down)  Is there any way I can tell a macro to half the final result and not every time but only when indicated. 

Roll20 can not do conditionals, instead you need to write your macros such that it will ask the player if this situation has occurred, then have the ability for the player to pick which action is the appropriate response - this could be a chat menu or a drop down query. There may be options with scripting to do this, but that is a pro feature, and more complicated.  Other posters may be able to give advice on this. For me, I'd have the macro give the players the information, and a pair of buttons, that call further macros, so that the player can decide which is appropriate.  I'd also use the default template for a little bit of nice formatting, but thats up to you.

You can use conditionals with the API script Power Cards. It is in the dropdown API library. I'm not very good with it, but the folks in the Power Cards thread can probably help you figure out exactly what you need.

Thank you, gonna end this thread and ask I new question as I think I have figured out something but have a new problem.