This is the trainning spot guide
about Mercedes in Maple Legends. Now check it out.
1 ~ 10 : Mercedes start off at level 10 so... skip.
10 ~ 30 : Go to Nautilus Harbor, start your training on Blue ribbon pigs, you can move over to the maps on the right as you level, in the end, you will end your 1st job training in the map where Jellyfishes resides(*notes). Alternatively, you could go The Golem Temple before 30.
*Notes: Those maps mentioned was introduced when the first legend patch hits.
30 ~ 50 : Now, you could start your Mushroom Kingdom quest or Kerning Square. Don't forget Ludibrium PQ which gives godlike exp at this level. Also, if the 1+1 event is activated, drink your potion, it will bring you to level 38 instantly.
50 ~ 70 : At this level, you could start training on Trojan Horses. Once you hit 62 or 64, go for Omega sector to take on Mateon. You could go for Zeta Grey if you want, it's rumored that it drops Angelic Blessing Ring Recipes. Do not forget you could take on Monster Park as well.
70 ~ 90 : There's a lot of training ground around this level. Deserts in Ariant, Labs in Magatia, Verne Mines, Mulung area are all suitable. When you hit late 8x, MP3 is a good idea too.
90~100 : MP3 or Homunculus are great, Captain and Krus are nice too, it's your preference.
100 ~ 120 : Now you can move to lower area of Ludi, ghost pirates and dual ghost pirates are good idea. If you don't mind how pain Death Teddies hits post 11x, you could start your Angelic Blessing hunting in MDT map, of course, training there is fast for a Mercedes as well, you have a skill named "Updraft" remember?
120 onwards : You could continue in Ludi at 12x but later on PQs and Monster Park might be your only method to train, you could also do some Zakum arms run at 13x~15x level.