This is a fairly old Manalink bug that I couldn't reproduce with the latter and the same settings, so seems to be Shandalar TH1 specific:
- At least 1 Burgeoning and 2 Valakut, the Molten Pinnacle in bf (and 5 Mountains), 1 land in owner hand
- Opponent play a land and trigger them all, the legacy damage card will not resolve until another damage is registered



Attached are savefile (last one called xxx) which will load a direct encounter with Undead Knight test deck loaded (deck included in the archive), don't forget to backup original files.