Just went into the Top 50 and my opponent played Mark of Gravity and Mark of Aether (see attachment).
Not much of a problem because they're just essentially pillars, but figured this might cause some problems if someone had one of these + pendulums/ weapon that gives more damage from marks.
I heard about some people playing marks a while back, but I'm sure I also read that it was fixed.
EDIT: I'm able to steal the marks.
Also EDIT: He went on to play other marks during the match
Final EDIT: I think the marks give relics in the spin because I won 3 relics.