I suggest adding an option to heal the player I am attacking.
Many players attack you when you are not around then when you come back they are low on health therefore you cannot retaliate.

to set some controls it may work like this:

1- healing cost is 1.5X the normal cost to heal this player.
2- the player must be equal or higher in level than you. (eg. you cannot heal a lower level player and attack him)
3- you can only heal this player once every 4 hours "or so"..

any ideas/ feedback? I think this feature will fix some serious balance issues with the way the game is currently setup due to players being on different time zones and all.