I wasn't able to use
Heritage Druid with summoning sickness,
Bump in the Night on stack said it deals damage to player (which is not true), and
Xathrid Necromancer produced untapped tokens. Can't tell you more about it...
New issue: I can see cards that opponent puts on top of library with
Sylvan Library.
Another thing: If you target
Cytoplast Root-Kin with its own ability with
Doubling Season on table, it will get extra counters, meaning that it got a counter removed and then added. This is not right because the rule 121.5 about moving counters specifies:
121.5. If an effect says to "move" a counter, it means to take that counter from the object it's currently on and put it onto a second object.
If the first and second objects are the same object, nothing happens. If the first object has no counters, nothing happens; the second object doesn't get a counter put on it. If the second object (or any possible second objects) is no longer in the correct zone when the effect would move the counter, nothing happens; a counter isn't removed from the first object.