what dungeon is the best for farming cosmic evo rune?

[Bakura]

The cosmic dungeon, hands down.

The Mayan Dungeon dropped 10 cosmic 1* t1 ruins for each level of the dungeon the first time, total 20, then on replay of them if it drops, it dropped 3.
Also, 25 ironite, and various talismans.
There are 2 parts (or levels).... the most difficult by far was the Shaman Ed w/ Mayan prietesses.... they jacked them up. Then in the other level, Necropolis has a tali I have never seen before.
This was great, immediately leveled up a Yellow T3 cosmic to max....has near 19,000 hp.