If an artifact planeswalker activates a + cost loyalty ability and it places a counter as a cost, Doubling Season doesn't get to apply.

If the same thing happens with Winding Constrictor out, does Doubling Season just double the counter placed by Winding Constrictor or both it and the loyalty counters placed as a cost?

Excerpt from 614.1 “Such effects watch for a particular event that would happen and completely or partially replace that event with a different event.”

So essentially is the Winding Constrictor replacement effect completely replacing the event by replacing all the counters and adding one more or is it partially replacing the event by just adding one more?

Edited Todd Bussey (Sept. 28, 2017 12:52:51 PM)

For an example of a partial replacement, see enters-the-battlefield-with-counters abilities such as Bloodthirst, which look for the event of an object entering the battlefield but don't specify something else that happens instead, simply modifying the parameters of the original event, which still occurs.

Winding Constrictor, however, is a complete replacement, replacing all of the “one or more counters (being) placed” with placing “that many of those counters plus one”. As such, Doubling Season would double everything, not just the one additional counter.