Milestones in the game

Well, on a whim I attempted to beat the beast on madness last night. (I'm of middle level about 64); I didn't think I had any hope as my characters are not fully sharded yet and I don't have any of the great talismans, and what I have are not maxed yet. I actually won to my surprise-but not without the help of a trooper 's seventh son Eddie. My team was vhe, pharaoh, seventh son, angel of fear and Clair. I only managed two skulls as they had some damage.
I'm thinking that the next milestones in the game would be getting enough skulls to open all skull quests, finally beating the level in bnw to earn the coveted chance talismans, and finally reaching warlord in pvp. On a good day I usually only reach 1700-1900 points. What other milestones would you say exists in the game that is not already an in-game achievement?

To be honest the biggest possible milestone in the game would be finishing rank 1 in PvP. But realistically the coolest milestone in my opinion is getting all the characters.

For me the last milestone was to be #1 in PVP, did it twice and now I just stay for the fun and the new characters. Looks like you still have a lot to do before the boredom catches you.