Burrowing's effect states:
Deal 1 extra damage on Tokyo. [...]
Does this mean,
"Deal 1 extra damage [to the Monster] on Tokyo."; or
"Deal 1 extra damage [when your Monster is] on Tokyo."
I believe it is the former, because of the wording on Urbavore, "when dealing any damage from Tokyo." Although, it might have been shortened due to lack of space.
Does Burrowing increase the damage from a non-attack? For example:
{6} Acid Attack: Keep; Deal 1 extra damage each turn (even when you don't otherwise attack).
{3} Fire Blast: Discard; Deal 2 damage to all other monsters.