According to Wizards of the Coast, this card was subtle, but powerful and the benefit that it provided came at too low a cost. Due to the probe functioning as a cantrip (draws a card) and costing a single Phyrexian mana, it allowed players to peer into their opponent's hands for the often negligible cost of two life
Most importantly, the discount applies to one Dragon you cast each turn, which means, thanks to Renari giving our Dragons flash, you can now cast a Dragon on each of your opponent's turns as well as your own for a much cheaper cost
This is still true today
Luckily, if your deck is built to handle it (and maybe youve got cards like Kronk, Laid Back), this "tiny" downside wont even make you flinch
(More on Sagas later.) If you have a bunch of cards in one color that want you to play historic cards, then perhaps you want to pair that up with the color that provides you with the most legends