Past Fragment Summon Rush
https://hellhades.com/past-fragments-event-summon-rush/
FYI - if you've missed out on any of those in the list, you *absolutely* should be doing this. Vlad and Supreme Elhain are admittedly not the most amazing, but both still have use, especially for newer accounts. The other four are endgame-level champs.
And, for Plarium - this is a great idea. Do more of these :) My 95-fragment Kreela is waiting!