Bone Wall summons in ethereally and with an awesome summon-in animation - but Bone Prison just abruptly pops in with no creation animation. I know legacy did this too - but why? Just a fraction of a second animation would not disadvantage players using it.
The Bone Prison could even functionally be there immediately, with just a graphic change in the beginning as it is being created. This would make Bone Prison look sooooooo much cooler and be so much more fun to use.