OK ground rules:
1. This is not a rumour thread, DON'T TREAT IT LIKE ONE!
2. Basically the idea behind this thread is to say what you would change about the current dex's if you were a writer for them. This can include fluff, rules the 'Why collect a such-and-such-a army?" bit at the beginning, whatever. Just try and justify it
3. Not so much a rule but more like advice; don't make big walls of text or try to re-write the ENTIRE codex.
Right to start off, I would make a vehicle in the eldar dex that has an "assault vehicle" type of rule. It is so annoying trying to get a squad of aspects into combat when your opponent sees the transport, takes the turn they have before they're assaulted and redeploys their unit. Honestly, something like a Venom, 5-man squads, would be perfect! Would definitley make the eldar more mobile; like they're meant to be