There are a lot of similarities between Woolly Thoctar and Watchwolf, as each pushes the envelope of what a vanilla creature can do at its point on the mana curve
In other words, Proliferate lets you put more good counters on your cards which already have good counters on them, and put more bad counters on your opponents stuff with bad counters
Should you play the self-mill version of the deck, however, this will recur some strong cards more often than not
You can damage your opponents, remove blockers, and pressure their planeswalkers all while punishing other players for taking basic game actions
As always, it pays to follow Martin Juzas prerelease principles: build a smooth mana curve, respect your mana base, and dont forget the fundamentals