Complex sentence: In the Age of Apocalypse storyline a Bastion existed, as evidenced when the X-Men are discussing Abyss who is the one "rumoured to have replaced Bastion".
Split into simpler sentences: In the Age of Apocalypse storyline a character named Bastion existed. When the X-Men are discussing Abyss, they describe him as the one "rumored to have replaced Bastion".