Using a Rek tunnel reduces E cooldown a bit
Despite Rek having all these interesting tunnel play capabilities, nobody ever uses them. E is basically a gapcloser that leaves you places to ult to, not a strategic tool for teamfights. You can't really set up a tunnel network for a teamfight because if you try someone will engage and you're out a gapcloser for a while. This change would let her set up a whole mess of tunnels if you leave her alone for 30 seconds without really changing much else (she can't really get extra Es off in a fight unless shes in her mess of tunnels... in which case odds are she wouldn't need to E anyway. Actually maybe "reduces the current cooldown by 30%" would work better to deal with that.
Also "for the first 30 seconds tunnels take twice as long to kill" would let them stay up in teamfights more easily.
Yes, this would be a buff to a top-tier jungler. I don't care, just hit her numbers or something. I'd take a AD nerf if this brought her in line with her more strategic patterns, because that would just be more fun. I feel like Riot didn't commit to what Rek was supposed to be and let her become Vi 2.0, probably because the tunnels don't really fit with this game (see Bard). But it would be fun to try.
Not trying to make a complaint thread, I love Rek, it'd be cool to massage her a bit and bring out her potential to be interesting.