Builders Bane deals damage to each player equal to the number of artifacts they controlled that were put into a graveyard this way
It just depends on Eiichiro Oda and how he wants to tell the story at the time
If Lorehold/Boros gravebreak is ever going to take off, this planeswalker commander will have something to do with it
Although the ninjutsu ability has the creature enter the battlefield attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example)
The other group of cards you will want to take a hard look (prioritizing on the same basis) at are the ones that definitely wont be in MM17, including: Blinkmoth Nexus Cryptic Command Engineered Explosives Glimmervoid Grove of the Burnwillows Horizon Canopy Inkmoth Nexus Karn Liberated Mishras Bauble Saffi, Eriksdotter Valakut Priority Exits (If You Can) Given how much of this set is going to be bought and cracked in the next two months, you have already missed out on some key opportunities to sell off staples like Cavern of Souls and Liliana of the Veil
But both are pretty good rares so its worthwhile to remember how party works
