Four mana for a 2/4 is way below rate for 2025 Magic, but luckily Yshtola has a weighty bag of tricks up her huge white sleeves
Jumbo Cactuar is a 1/7, which gets a +9,999/+0 buff when it attacks
Considering the cards mentioned above, it is clear that this Deck strategy revolves around keeping pressure on your opponent by Challenging and Questing
You get one of these glossy box toppers in a Set or Draft display, and two in a Collector display
Based on this experimenation, it seems like the Sapphire/Steel deck is more aggressive , with new cards boosting Strength and increasing Resistance, while the Amber/Amethyst deck is more about mitigating and removing damage
And you can keep him safe by just not questing with him while you deal with whatever threats are on the board