This was enjoyable if a little run of the mill. Anthony Head continues to give a great performance, and McCoy is brilliant as ever. I think the plot here is a little on the weaker end, but I think the worldbuilding and ideas on display here bring it back up.

It's very rare you get the more mythical in Doctor Who without a technological explanation, and it's nice to see that not only do they not explain the relic or the spiritual aspects of this planet in this final(ish) part of the saga, but also I really like the use of souls as almost fuel(ish) here is interesting, almost reminds me of Class.

The implication that The Doctor had been going around without his soul (or at least without all of it) for at least one full regeneration is something, not sure what the implication there really is, but the way Greyvorn then uses that to draw on The Doctor's knowledge is fun and making him a more deadly enemy. I also like that you get a bit of The Doctor dealing with the destruction of Excelis, not much, but it's there at the end which is nice.

Overall a 6 out of 10 for me.