With PTE taken out of the game the siren mech is far too punishing to players, forcing us to have a DK tank use magma shell to get under her to rez players out of range (not practical, situational), or have the rest of the group wipe reset based on one death.
What we need is an invisible half-wall around her so that remaining players can rez players who died under her without being hit by her persistent AOE, or some form of collision on the boss that prevents players from getting out of rez range.
This was needed even before PTE was taken out of the game and is needed more than ever.