Level 20 was a blur on both my Rune-keeper and Captain. Literally. All I did was the Skirmish Tutorial and one skirmish, and it took me from about 10% into level 20 all the way to level 21.
The skirmish I picked was “Siege of Gondamon”; it was either that or “Trouble in Tuckborough”, the only two choices at level 20. I had rest XP on both chars, which was used up during the course of the skirmish (when I noticed that I spent some destiny points to buy another 3 bubbles worth).
I think what really made a difference, as far as XP gained, was fighting lieutenants. Especially the two at the end of Siege of Gondamon – Ingithor Blackhand and Nethgarch.
I’ll try Trouble in Tuckborough sometime soon on my lowbies.