The Star Store doesn't update that frequently, and often, the cards aren't 'must haves', but I want to make sure no one misses these:
Inferno
Practically a must-have in Ramp Magic. Often, you make it to 7 mana by the skin of your teeth against aggro, and you need to immediately clear their smaller creatures. This firmly changes the tide and wins you the match.
Charging Oryx
Grab 2x meteorites. We know daily P2E will be influenced by card quality. Oryx is a great card. Personally, I have 10 copies in order to make 2x shadows when the forge is upgraded.
Ares' Runeblade
Definitely want to have 1 or 2 of these. High-mana relics aren't currently in the War meta right now, but the CSR has a card coming out that reduces the mana cost of relics. If this goes live, it will change everything.
Stack the Deck
I'm not picking up a shadow of this one. Mainly due to the cost compared to how niche it is. Only really played by Mill Deception (which isn't that popular). If you are just busting at the seams with stars, then maybe.