Slot 5 has a nonfoil borderless or sketch frame card, either rare or mythic
Graded Population Report: Meowth ex #121 Visualize the distrbution of grades in the chart
If you no longer have coven at that point (because, say, somebody pointed the pointy end of Swords to Plowshares at one of the creatures in your coven), then nothing happens when the trigger resolves
The deck starts by casting a number of powerful, efficiently-costed vampire creatures with strong secondary abilities including Clavileno (card draw, creature tokens), Cordial Vampire (+1/+1 counters), Drana (+1/+1 counters), Dusk Legion Duelist (card draw), Florian (filter/draw), Mavren Fein (vampire tokens), Nullpriest (lifelink, menace, reanimate), and many more
I recommend just practising a lot - that's the most important part
That means the only time Silhana is a viable option for a card quality card is when your deck specifically scales with and utilizes creatures