Coming in at a minimum market value of about $35 on TCGplayer, this is the much rarer half of a two-card combo involving Exquisite Blood and Sanguine Bond
The odds on this are very, very low: as laid out in the offering rates, getting a gold card from any pack you open has the following odds associated with it: Cards 1-3: 0% Card 4: 0.040% Card 5: 0.160% Wonder Picks
In particular, Whirler pairs nicely with Era of Innovation, effectively giving you the ability to assemble your own (poor) version of Thopter Foundry / Sword of the Meek
If you still had your Onslaught cards you could basically just take a turn every turn
We don't care about getting it cheaper, it's good at nine mana
For example, the Base Set Charizard was unevenly distributed in Base Set booster packs, which made it even more elusive