Senna has no dash, so she gets caught outright by Rell's Flash + Ferromancy: Crash Down (W) engage. Chained under Ferromancy: Crash Down (W) - Shattering Strike (Q) - Magnet Storm (R) CC, she can't leverage her long range and melts.

Soraka has no dash and her only self-peel is the Equinox (E) silence, so tanky Rell eats the silence, closes in with Ferromancy: Crash Down (W), knocks her up, and finishes her.

Until Crescendo (R), Sona has no hard CC to interrupt Rell's engage and no dash, so she gets caught and killed by a single Ferromancy: Crash Down (W) dive.

Seraphine has no dash to escape Rell's Ferromancy: Crash Down (W) engage range, and before she can land her Beat Drop (E) root, Rell reaches her first and knocks her up.

Janna's Howling Gale (Q) and Monsoon (R) knockbacks interrupt Rell's Ferromancy: Crash Down (W) engage and push her off the ADC, neutralizing all of Rell's initiations.

Brand chips down the walking-in Rell with strong pre-5 poke, and interrupts her mid-engage with the Pillar of Flame (W) - Sear (Q) stun combo.

Vel'Koz chips down the dashless Rell with long-range sustained poke from Plasma Fission (Q) and Void Rift (W), and even when she closes in, Tectonic Disruption (E) interrupts her engage, so without Flash she can't even approach.

Karma neutralizes Rell's engage with the Inspire (E) shield and move speed empowered by Mantra (P), and chips down the walking-in Rell with Inner Flame (Q) poke, taking the lane lead before Rell can close in.