kitty pryde at least in DOFP, gained the extra ability to chronoskimming too, which as people interpreted advanced form of phasing allows to phase outside the time space, and into the past. sending your conscieness into the past. this is the same aiblity that eren in ATTACK on titan used on his past incarnations)
Yeah, anytime anybody asks this question that’s my first thought. Either that or like Shadowcat and the ability to phase through things. 
kitty pryde at least in DOFP, gained the extra ability to chronoskimming too, which as people interpreted advanced form of phasing allows to phase outside the time space, and into the past. sending your conscieness into the past. this is the same aiblity that eren in ATTACK on titan used on his past incarnations)