Hmm that's weird, I just found out what mission I wanted before actually looking here, and it fell on #27 for me, Obtain any 30 legendary cards. Thing is, I was saving a legendary chest for that x) Many thanks still! (I'm currently at #28, not sure I'll make it in time for the mythic card unfortunately...)
Gotcha, i didnt look at #27 and assumed you meant the specific event legendary card. My bad. I finaly hit #33 which turns out to be "get 2000 pirate silver." I dont think i will be able to get the mythic with how much time this goal will eat up, in addition to all the cool down times involved with beating legendary Dungeon rooms in #34 and opening 5 chests in the shop in #36. I don't have enough crystals to buy any chests so I'm going to run out of time. What a bummer. I would be able to complete goals 35, 37, 38, 39, 40 and 41 with only the time it would take to win some battles.
One thing I learned is that I will not defeat all the Event monsters immediately, and will save those battles for when I need to "get pirate silver". I would probably be able to get the mythic if I had a few of those battles left and the hundreds of silver they give you each battle.