Dude1818 recent design reminds me of my Jawas drinking Blue Milk deck from the old Star Wars CCG. I thought it would be neat to move the drawback into the cost of the card... otherwise, it isn't very different with what he's toying with.

Nice; means you can't cast it without the downside actually mattering. And the flash means that you don't need to worry overmuch about not being able to drop it turn3 if you played first, as you can just do it in your opponents turn3 after their third land hits.

Also quite an interesting answer to the problem of manascrew - could be adapted to big creatures that can only hit if manascrew isn't going on.

Yeah, this is very elegant.

A potential problem with this mechanic is if the opponent just doesn't have anything to cast on turns 3 or 4. But that's fine for this particular case, I think, because this is an exceedingly Spider card: both literally and in Anthony Alongi's animal metaphors. This is a reaction to what the opponent's doing, so if they're not doing anything that needs 3 mana, well, I guess you don't need your big sneaky surprise reach blocker.