Then upgrade bow + belt ASAP and try with that.
I assume from your screens that you are playing Singleplayer. You should download the Offline tools:
viewtopic.php?f=40&t=342Then you should respec your character and put every point you can into ecstatic frenzy, wyrmshot, dragonlore and sun strike, something like this:
https://skillplan.median-xl.com/planner?id=00sICH5oWith this setup and a little bit of patience you should be able to clear TA safely
Dont waste points on Phalanx, it costs too much mana right now and Wyrmshot is the clearly superior skill