Drowner of hope says that it disables all opponent creatures whenever you play a colorless creature, but not all creatures are triggering this ability.
The scions that the drowner spawns DO trigger its ability, as does actual colorless creatures such as Ulamog’s Dispoiler.
However creatures that are listed as a color, but have Devoid do not.
I am unsure if this was an oversight or was intentional. As in regular magic the gathering, any devoid creatures are treated as colorless in all aspects.
Devoid creature are not counted as colorless.
This topic has already been discussed many times.
Maybe they will change it, maybe they won’t.
For now it is working as intended.
They said they are investigating it. But that was probably months ago, so I suppose devoid will never be colorless, which is lame.
Hahaha. If only.
“any devoid creatures are treated as colorless in all aspects” has never been true in MTGPQ. Devoid in MTGPQ has only ever meant “gains mana from void gem matches”. Yes, this is ridiculous. Yes, this completely breaks all the Eldrazi synergy. Yes, the devs are aware that this is a problem, and they’re considering fixing it.
But for now, haha, nope, devoid does not mean colourless in MTGPQ.