Martijn van Steenbergen

Right now move events don't have the last known information of an object associated with them so you can't see, for example, if an object was a creature when it...

When some but not all targets of a spell or ability become invalid, as many effects as possible are applied. Currently what actually happens is unspecified; this needs to be...

Some effects create delayed triggered abilities. For example, Chandra, the Firebrand says in part: "-When you cast your next instant or sorcery spell this turn, copy that spell". This effect...

Some non-permanent objects (instants, sorceries, triggered abilities, activated abilities) create replacement effects that are not tied to a specific object and can therefore not be stored in a single object,...

Some cards allow you to choose new targets for a spell or ability on the stack (Reverberate, Redirect).

Some cards trigger not on events but when a certain state is reached in the game (Phylactery Lich). To fully implement the rules for state-based triggers like this one, they...

Some cards ask players to separate a set of objects in piles (Sphinx of Uthuun). A special kind of `Question` needs to be created for this.

One card, Odric, Master Tactician, allows the active player to choose how the defending player blocks. More generally, some cards allow a player to completely take over someone else's turn.

Cards like Oblivion Ring and Stuffy doll ask the player to choose another object or player and remember that choice for later. Maybe objects need to keep track of one...

Certain cards allow you to look at parts of your library and move cards around (Augur of Bolas, Index).