The ability was written with different strategies in mind, so although it may seem like an aggressive deck, there's actually many angles to discover
So as you can see, the trick is not just to spot cards with low sentiment in some absolute sense, but low sentiment relative to what it would be if the card were fairly priced
A creature with Protection from a quality, let's say a colour for simplicity, can't be targeted by spells and abilities of that colour (like Shroud, that's regardless of who controls them)
Speaking of frogs, is Helga, Skittish Seer the first Bant Commander Id actually consider building
With a reasonable cost for the stats and an ability that provides Sapphire with a real boost, she might not topple the reign of Elsa, Spirit of Winter, but shell be a must-have in practically any Sapphire deck