You might be able to make an educated guess as to whether a card you need is going to be in a specific players deck based on their commander and perceived budget, but thats far from a guarantee as they are just as likely to have forgotten to include the card youre searching for or simply havent bought a copy of it yet
This white room pairs really nicely with Anim Pakal, Thousandth Moon, which can also make a big board when other creatures attack
The Water Crystal [Borderless] #333 (Magic Final Fantasy | Magic Cards) prices are based on the historic sales
Standard, though, is different
The battalion ability of Legion Loyalist and the battle cry ability of Hero of Oxid Ridge are the sort of cards wed add to the deck outside of a Goblin tribal approach
Blue Cyclonic Rift This card is often a precursor to a win, since resetting the board at instant speed means you can generally go off and combo win on your turn, but it's also a decent bounce spell for only 2 mana if you can't afford the overload, and it's a blue spell that can be pitched to Force of Will or Force of Negation, so just all around strong card