The Alchemist tapped the end of the staff on the air, and the battle began. Knowing he could not clash head-on with the crystal spears he aimed to divert and redirect them, if he could get a single Spell to reach Silas he would win.
He used the Infernal Twister Spell he previously deployed to strip Silas of his protections, so that any random Spell that could touch Silas would be the end of the battle. This was a strategy often used in battles between Mages.
There was a major difference between the power of a Rank 3 Mage and a Rank 4 Mage, that was far wider than between a Rank 2 Mage and a Rank 3 Mage. So he needed only a single opportunity.