Three mana sources were available, one each for earth, fire, and wind. Then, Banning Prerogative already lost its ability, shut down by Leon's Nullification Stone, and with 11 life left in his stats, it could be said if it was a race, Ahli was being left behind, the back of the pack.
And therefore, his game plan for this turn was supposed to catch up with Leon, even though it would surely not be able to pass him at all.
So Ahli took the first card out. Sparks of Change. It should be used to prepare his future draws, but Ahli had another plan that he would like to execute, and therefore, he needed this card to be a mana source.
SPARKS OF CHANGE
Fire Mana
[Magic Spell]
Deal 1 damage to any target.
Look at the top card of your deck. You may put it at the bottom of your deck.
Mana: Fire