I find Doomed Metropolis a very easy place to farm Source Marks just doing the daily content in the Doomed Metropolis Open World area. Just fly or run around fighting fairly easy enemy mobs and get lots of Source Marks. Of course, if you're in a REAL hurry, you can always just BUY Source Marks now in the Marketplace.
A large portion of this is going to also depend on Character Relevancy. Content that is too weak for you will no longer award any Source Marks. Basically, the best way to farm Source Marks is just to blow through the content that is slightly less than your level, beating it fast because it's easier. A raid that gives you 8 marks and is done in 10 minutes is better than a raid that gives you 10 marks but takes 40 minutes.
Don't forget that artifact catalysts are tradable so it's pretty easy to level a character to 30 and then slack off on raising their cr while you run all the T1 and T2 solo missions- then you just buy what you need and ship it to your main.
Is there a way of telling which ones are to low lvl for me to farm, i boosted my one character because of the free event thing.
Actually if you have a toon in cr53 you can get a lot of source marks form basically the half of the game, but you may need be carried through the instances by a friend
I find that this works very well for me..... There are 5 daily missions and three don't require you to actually attack any mob at all.. just run around and click stuff. Now the Doomsday bounty mission we get from Lois can be difficult to grab since you "NEED" a team but even if you skip that on off days you still leave with 4 Source Marks and I can usually be done and gone in less than ten minutes. Don't forget to do the weekly stuff... the kill all is not bas even solo (only requires you to defeat 99 not over 400) and you can usually find player doing the weekly bounty since it pays out well and is involved in feats. Both of those will hand you another 8 source marks. Now right off hand I forget but after around Cr 260 the marks stop and all you get is the Tributes but until then you can grab as many as 5 marks a day and add 16 a week on the "weekly" stuff. Now let's add a couple more quickies... Do the Vault mission daily (if you subscribe) and you get another mark, nth metal and an unattuned piece of armor that currently can go as high in CR as 240. Oh and the whole thing takes less than 1 minute. Back to Death of Superman stuff.. run the Last son of Krypton solo. Takes about 5 minutes or so.. less if your character has really high Cr and longer if you very low in CR. but again you grab a source mark, nth metal and an unattuned piece of armor that can get as high as CR 198. Again above Cr 260ish the marks stop and just the tributes drop as rewards. You could also hit the new Metal part 2 daily zone and grab 3 source marks a day plus there are 2 weekly mission paying out 8 each. Best part there is you can start running that as low as level 10 and any one above level 30 is welcome until the next DLC arrives.
Relevant content for you would be Death of Superman, Teen Titans: Judas Contract, Atlantis and Justice League Dark. Everything else under that will net you maybe 1 Source Mark per boss fight.
Solos/Duos/Alerts give you the chance of a source mark as loot in each boss fight. Those low level solos and duos are still worth it because of how quickly you can complete them. Gotham Warehouse solo has 5 boss fights, Gotham subway has 3 each run of solo/duo (and you can always que it again and quit if the coin flip at the start is the same until you unlock the 4th boss fight). The T3 duo of your mentor gives 2 source marks guaranteed each day with a chance of a third.
Cr 207-215 Sorce mark farm seems to work the best for me. In that range you are Cr relevant for 3 episodes. -Age of Justice (2 open worlds/2 alerts/ and 2 raids) -Riddled with crime -Earth 3 All have pretty decent soloable weeklies. Alerts pop relatively decent since people farm the OP collections from age of justice and riddled with crime alerts. Then if you factor in the current open world dlc that a lower level toon has access to you can easily farm 30 source Mark's per day on that toon. (Not counting weeklies)
I try to run everything I'm relevant for, which is Dark Gotham, Metal 1 and 2. Gotham no longer gives me source marks but when the next episode comes out, all the daemohedrons will convert into source marks. So I always try to have that last relevant episode currency maxed out if I can because that could be an extra 999 source marks. Most of the time I'm maxed out well in advance and buy vendor items to make money on then farm back to 999
just click on any instance in ur on duty menu. Around where it shows what min/suggested cr u should be it shows what loot u get based off cr. For instance it will say cr >178 gear. Cr < 178 gear + source marks
