Play vs. Put into Play

So these are different, but what happens when an effect says "Put the top card of your deck into play" and it's not an equipment (or similar) or ongoing (or similar)? Is the card discarded?

-nihil

Regardless of what it is, you put it into play and reslove any actions that card has. If it is a one-shot, you would perform the action then move it to the trash like normal.

The distinction between "playing" and "put into play" is only important when a card effect is triggered upon one of those actions happening.

I guess I'll chime in on this one - Can OmnitronX's base power be used on a deck that's been Mistbound?

Yes it can.