The Greentide of Remnant

When Da Great Green Prophet (after a mushroom ale/Waaagh Magic induced coma) gets a message from Gork N' Mork telling him to create a world-travelling gate and gathering ALL Greenskins to witness it (and eventually go through it) he does it. And soon, the Greenskins of the Old World find themselves wraped up in the ancient struggles of the "Newa World". How exactly will this end?