@sno: yes, totems stack with each other (i would think of with other types but not with the same type would be a useful balancing mechanism, so fire+earth is OK, earth+earth would only be one effect). as for which slots it will affect, adjacent does have some ambiguity to it, but i intended it for those which were in contact with it, so slot 7 is adjacent to 12, 20, 3, 8 and 16.
@ot: good point with "I think the increased totem hp is enough of an upgrade.", for earth i think that is valid, for some others, keeping the hp unchanged but boosting the power may be a good way to go.