Great card advantage
Frankly, Strefan isn't all that interesting with his clunky Blood token abilities, whie an Edgar reprint would have sent players into an absolute frenzy
Similarly, booster packs of cards are constructed in a way to feature four different rarities of cards mythic (one in every eight boosters), rare (1 per booster), uncommon (3 per booster) and common (10 per booster)
Players cant cast noncreature spells from graveyards: probably the weakest ability of the bunch, although it is relevant against Underworld Breach combos and random flashback cards which show up on occasion
Harmonic Sliver turns each of your slivers into artifact and enchantment removal - very useful for dealing with all kinds of different threats
If, however, your child wants to actually play the TCG, theres a couple of excellent starting points we can highly recommend, depending on your childs age and/or experience with card games in general