Edit: E4 Siren created. I would like to thank Exiled for re-creating E5 client as this was the main breaking point into making this possible. Cheers to you.
Epic 4: Siren Skills
Below are videos on what skills the former E4 Siren used to have before the Global pet remake in E5.
Siren Whip skill -
Siren Debuffs/CC -
Siren Skilltree -
Siren's Diabloic ballad (Illusion) -
I got the E4 Client and imported the E4 Skilltree database file and replaced it with the E5, with some minor tweaking i got the E4 Siren back, was pretty awesome to be able to play E4 again since she was my most favourite pet.
Above is just one of the examples, but all of the E4 pet skills like Orc, Yeti, BP, RP and Skelly were brought back as well. Also the old scaling of skills e.g. Spam Spells being extremely weak.
Disclaimer: The above is just there to show that it is possible to bring back E4, but I'm not creating/releasing this myself, this was merely for fun and so I can replay E4 Siren.
If anyone is interested into making an E4 server then feel free to do so from E5.2 server files/Cilent.