as the title says it just takes damage everytime i activate altar of repair and not recovering any durability ... seen few posts from other players having same issue: Done - Altar of Repair and Wand of Animation | MineYourMind Community Done - My problems with "Wand of Animation" and "Altar of Repair" | MineYourMind Community Done - Repair Altar | MineYourMind Community
Its working on the server ,sadly it seems to bug out if you are doing it at an area with alot of entities, means if you go to the nether and find a nice playce and do it there or fly away from your base and create a little platform it should work.
