We have the following game situation:
A Troll blocks a Dwarf Longbeard at a matchup. A Dwarf Blocker is also present at this matchup. No other player then.
The Troll rolls double Target Down. The Dwarven Player now decide to down his Blocker becaus he has Guard.
Now Pilling On will trigger. Which Player is now legal to be tackled? The Blocker? Or the Lineman?