Unlike basically everything else here, like people not understanding Special Summons that require tributes, I think that actually may be a bug.
There is a bug that prevents this card from working against Manga Ryu-Ran. Used against Pegasus LV30 a number of times and he just attacks my directly without giving the option to activate this card. However Mirror wall is given as an option if i've played it so not immune to traps.
It is not a bug. Summoning Manga Ryu-Ran isn't considered as Tribute Summon even if it does need 2 tributes. Technically, Tribute Summon is a Normal Summon that uses tribute. But Manga Ryu-Ran can only be special summoned, so it doesn't count.
How can Blast Held by a Tribute work on Dark Necrofear's effect that attaches it to a chosen monster after it was sent to the graveyard? Plus, Dark Necrofear can only be Special Summoned and not Tribute summoned.