I'm a little bit confuse about the following: Do you have to declare the full effect of your powers to the target?
For exemple, our fighter challenge the ogre chieftain. Does the Ogre known that he`s mark and that he has a -2 penalty to attack roll and risk interrupted attack if he don`t try to attack the fighter?
Another exemple: Our group is attacked by a mercenary swordmage and his allies. The swordmage use Ageis of Assault again our dwarf barbarian. Does the dwarf barbarian known the consequence of hitting one of the swordmage allies instead of him (before it`s too late and the swordmage teleport behind him to strike him)?
Our human warlord use Viper`s strike against a Kobold Dragonshield... Does the Kobold know that it will provoke an opportunity attack if he use is shifty power?
Our eladrin wizard, want to cast Scorching Burst at a group of goblins... Obviously this attack will be a lot more potent against minions. Does the DM tell us wich one are minions (or a nature knowledge roll is require to determine the type of adversary)?
My take on this is that players need to declare the full effect of their powers and the DM will have to try not to take advantage of this knowledge against the players.
On the other side, the DM should keep secret the effect and let the players try some knowledge rolls to idenfify the possible effect or the source ... but monster knowledge rolls are fine for 'monster' but how do you known that the mercenary is a swordmage? Does a nature roll of 20 can reveal is name, type ,keywords and powers? I don`t think so... Is it common knowledge then? For exemple, if you are cursed by a warlock, do you known by default that you will loose more hit point if he it you? How do you known that you have been cursed by a Warlock since there is not apparent effect?
Thanks!