correct me if I am wrong, didn't it said somewhere it prevents monster effect from activating on the field but trigger effect still works or something?
'Angel O7' only prevents effects which ACTIVATE from activating. Since Continuous Effects like Vasal's effect do NOT activate, 'Angel O7' will not prevent them from being applied.
For all those who don't have union attack and want to use riryoku instead, you may add a trap card 'Altar for Tribute'. In your second to last turn use it to send Angel O7 to graveyard and then in the last turn you may use the effect of summoner of illusions to special summon the fusion monster from your extra deck and then use riryoku to gravekeeper's vassal or piranha army
Mr.WRWR
Anoymous
