To get an eternal trophy you’ll need to reach at least mythic (but very rare) or eternal league (you’ll get approx 1/5 trophy)
You’ve 2 types of eternal trophies, the best so far is the bloodless one because it reduces a bit bleed dmg with clotting (and atm 90% of players are using bleed because it’s unbalanced)
The higher floor u’re opening the chest, the better will be your item (better stats rolls, higher level of eternal item, etc)