CGC, taking advantage of this, will include designations for a lot of these issues in their variant field, which you can request on your grading submissions with them
If an Adventure spell leaves the stack in any way other than resolving (most likely by being countered or by failing to resolve because its targets have all become illegal) , that card won't be exiled and the spell's controller won't be able to cast it as a permanent later
In a combo or aggro meta, you really cant afford to sit around and naturally draw Fluctuatorthis is where you must try to mulligan for it
but with Delve and Convoke, casting it is very easy, and it can even be cast from the graveyard
"Shield" is not an ability that creatures have and shield counters are not keyword counters
If dual-ink cards have to go into decks that use both ink colors, those cards will need to be extremely powerful to incentivize players into set deck builds