There should be no need to buy since 2.1.....Party Finder!!!

Otherwise find a decent FC. Most will have a few players after their second relic (or third or even fourth) who have the exp to help you through.

Short of that you cant underestimate experience so practicing in DF can help. Just bear in mind the hardest part of DF Titan HM is managing the 7 adds!! (lol )!!!

Read some guides, watch vids on Youtube. Learn his rotations and it is much easier as you can pre-empt what he is about to do.

I don't understand why DF groups are always so poor. Surely the reason for running Titan HM is to get your hyperfused ore for relic quest...so surely if you are in it you want to beat it (Fresh, curious, AF geared Lvl 50s excepted of course...come on, be honest, we all did it....you can spot them from a mile off)

If you want to buy then it is your money and your account (sure SE wouldn't approve) but a bit of perseverance might pay off and think what you can do with your 500k....)