Should there be any logic on the activity class?

I was recently reading about design patterns and especially about low coupling and delegation.

I was wondering, whether there should be any logic on the Activity class or if it only serves the view.

E.g. I have an activity called BattleActivity and that is supposed to work as some kind of session between two players. A lot of Push Notifications happen there, also the class works as an Observer, so there is a lot of comminication going on there.

Right now I am trying to figure out what logic could I move to a separated object(and whether I should) and then just work with the activity.

Example of one of my methods on the activity:

private void postCastedSpell(final int spellId) {
        Call call = StaticGlobalContainer.api.postSpellToBattle(Integer.parseInt(battleId), Integer.parseInt(MainActivity.CURRENT_USER_ID), spellId, 100);
        call.enqueue(new Callback<User>() {
            @Override
            public void onResponse(Response<User> response, Retrofit retrofit) {
                User user = response.body();
                if (response.code() == 202) {
                    // 200
                    Log.i("Posting spell to battle", "Success");
                    Boolean affectedUserIsOpponent = isUserOpponent(user);
                    if (affectedUserIsOpponent && user.currentHp<1){
                        StaticGlobalContainer.battleOnResult(Constants.WON, getApplicationContext());
                    }else {
                        updateBattleLog(affectedUserIsOpponent, user, spellId);
                    }
                    // TODO: do something here
                } else {
                    // 404 or the response cannot be converted to User.
                    Log.e("Posting spell to battle", "Error:" + response.errorBody());
                }
            }

            @Override
            public void onFailure(Throwable t) {
                Log.i("HttpRequest-Post spell", "Failure");
            }
        });
    }