use the following order to choose chests; 84 -> 39 -> 56 -> 162 -> 23 -> 55 -> 81 -> 30 -> 33
That gives you the most 'Grand Prize efficient' order of the chests, and following it AND fully completing all the quests + daily log-ins is the most RNG-proof way to get all required artifacts...
Now, pick-up enough incidents from around your city and maybe get a couple lucky pulls of extra currency from a few chests, and it's also very doable to gain a 2nd copy of the Lv1 building as the IIRC 14th grand prize.
(...should be the 280 stardust mark.)
This is the method I
always use, (ie: ignoring daily special %'s and just focusing 100% on most efficient grand prize picks), and I've managed to make 14+ grand prizes in every event this year while spending 500 dias only once. (IIRC, I got skunked
hard during the Spring event & had to buy 100 currencies to make the last 3 moves for a 2nd Lv1 Ashen Phoenix)
Only event I've spent diamonds was the Sorc event, and that was to fill out a 2nd full set, though I still made 13 grand prizes before throwing bags of shiny rocks at that event.