Regarding the variant rule for Warforged and Rust Monsters:
1) A rust monster's attack only affects nonmagical ferrous metal armor plating, as per the MM (I assume that is already the intent).
2) You might want to consider giving weapon attacks advantage against the warforged character instead of imposing the variant form of the Exhaustion condition - it makes the bookkeeping a little easier, for one thing.
As to the duration of the effect, I would be inclined to home rule it this way:
-If a warforged character gets hit by the rust monster only once, the warforged will need to take either a short or a long rest to spend time repairing its armor plating in order to stop granting advantage to weapon attacks by its foes. This requires that the party has the needed tool proficiency and materials. If not, the warforged PC will need to get to a place where these things are available.
-If the rust monster successfully hits the warforged character more than once, only a long rest will allow the character to spend enough time to repair its armor plating in order to stop granting advantage to weapon attacks by its foes, and the same requirements for repair apply.
1) A rust monster's attack only affects nonmagical ferrous metal armor plating, as per the MM (I assume that is already the intent).
2) You might want to consider giving weapon attacks advantage against the warforged character instead of imposing the variant form of the Exhaustion condition - it makes the bookkeeping a little easier, for one thing.
As to the duration of the effect, I would be inclined to home rule it this way:
-If a warforged character gets hit by the rust monster only once, the warforged will need to take either a short or a long rest to spend time repairing its armor plating in order to stop granting advantage to weapon attacks by its foes. This requires that the party has the needed tool proficiency and materials. If not, the warforged PC will need to get to a place where these things are available.
-If the rust monster successfully hits the warforged character more than once, only a long rest will allow the character to spend enough time to repair its armor plating in order to stop granting advantage to weapon attacks by its foes, and the same requirements for repair apply.
