For upkeep with the karma (and to have a plenty when you aim for legendaries one day) get yourself https://wiki.guildwars2.com/wiki/Karmic_RetributionEspecially on the LWS4 maps with plenty of mobs to kill (Sandswept Isles, Jahai Bluffs). I racked up 4mln karma in less than 2 months. Also - there are guilds that run trains to farm karma & volatile magic on the LWS4 maps - there is one every 6 hours - just keep an eye on LFG. One starts 45min after reset in THP.