The most important thing in this tournament (and probably in any) was to get out of the starting area as quickly as possible and then build an optimal route.
I made a mistake by running after vampires and liches after joining the gargoyles. I should have immediately taken the Barbarian Castle with a Grolem, and only then gone after the vampires; I estimate that would have saved me 4-5 days.
By the way, if anyone is interested:
A brief walkthrough....
In the first week, we collect resources and all the chests for gold, which gives us the construction of a Behemoth dwelling.
In the second week, we defeat the demons and loot the gnomes, which gives us the construction of a town and a castle.
In the third week, we leave the starting area: on day 17, we clear the Sorcerers; this is a difficult battle because we can't lose a single Behemoth. Then we move on to the Necropolis... there we immediately gather an army of vampires, black knights, and dragons, then we capture the Behemoth dwelling (+1 Behemoth) and free Alex.
Then we run to capture the gold mine and quickly go to the Elder (along the way, we join the gold dragons). At the Elder, we get two Rust Dragons and buy another one on the way back.
Then we run for the gloves, and after taking them, we go for the Phoenixes and get into the boat (around day 31).
We leave the vampires to Alex, and Celt runs for the gargoyles. After joining them, we take the Knight Castle, then the Barbarian Castle...
Then we sail to the island for the liches and vampires. After the battle at the outpost, Alex gives the vampires to Celt, and a large number of vampires join us, hooray! Then we run, join the liches (another hooray), and clear the path to the artifact...
We run back and get into the boat (along the way, we buy a Sapphire Dragon; it helped a lot because its "fear" effect works even on the Black Dragon).
We sail through the whirlpool to the blue faction (top right) and run to capture the Barbarian Castle (along the way, we take the sword).
After capturing it, we go to visit Hacker, where we upgrade the vampires and take the castle... (at this time, the enemies are trying to attack my castles, so I have to skip a turn and tell them that they are acting incorrectly... and Alex goes for the necklace).
Then we run again to the blue faction to collect the artifact and, along the way, clear their first castle.
Then we get into the boat (at the very bottom) and clear the Wyverns, then we sail to visit the blue faction and say goodbye to them...
We clear the Efreet and get the Archangels (third hooray), then we go to meet the Black Dragon, and after that, we teleport to the Knight Castle. There, we give Desser the Captain's Hat and send him for the corresponding artifact (to the Bog Witches), while Alex, meanwhile, takes the artifact after the Black Dragon and runs for the artifact at the very bottom...
Celt goes to free Joker, and after freeing him, he goes for tea with Magnus. After that, Desser takes the artifacts from Alex and teleports to Celt, and passes them on...
Celt collects them, and... that's it!