[Osamakurdi]

I think that what are you trying to find ?

Code:

public OnPlayerTakeDamage (playerid, issuerid, Float:amount, weaponid, bodypart)
{
    //Do something
}

You will take the issuerid and check if he is from team1 and check if playerid(who took the shot) from team2
If this statement is true you will set the playerid's health to 100(or his health before shot).