The Elementals sent that aren't the Kings are not that strong, and move in groups of 10-20. They are made of Earth and fire, and the Kings are about as strong as some of the strongest members of the guild, if let out, the Golem is a Major Earth elemental, sealed inside Tina, it is similar in power to Sarah's sealed Being, when the Elemental Kings take over their host's bodies, Jake suddenly is on fire, one eye glowing orange, speed is increased, and his fire magic is doubled. Darryl's transformation is a little different, he has rocks around him, his strength is increased and has a natural 5% resistance to most magic, due to the defense power of the Elemental King of Earth.
Darryl's a minor lord in Kelan, and specifically the Lord of Mail. He has the town guardsmen ready to deal with anything Vlad throws at him, and the Elementals are supplied like extra soldiers, I'd only have control of the Kings, I would hand over the Elementals to you. He personally wants to reinforce the Stormbreakers.