This should at the very least be explained in the description, but probably should place a wall on the branch entrance as one would expect. This bug is 'major' because this could break streaks or kill characters due to no fault of the player, especially because it seems like the natural thing to do to then escape via the branch entrance when you can see it isn't covered by a wall. Furthermore, the Tomb card is intended to be a reliable emergency escape when enemies are not next to you (especially from high-level decks).
The screenshot shows me losing a life on a felid to this mechanic, having evoked the Tomb card from a legendary deck (with 6*, 8 invo, I would expect the tomb to be perfect at this power level) standing on the dire flail, then moving onto the Lair entrance to try to escape downstairs, then getting shot down by the yaktaur. (I have also confirmed in wizmode that walls are placed on up/down stairs as expected, but never on branch entrances.)
2018-03-04 Tomb card and branch entrance behaviour.PNG [^] (608,345 bytes) 2018-03-04 13:39 
