Zach's question stunned them both. If they got a contract skill with every familiar they summoned, and they summoned a whole swarm of familiars, they would get a bunch of incredible contract skills that would let them do all kinds of crazy things. They couldn't even imagine it.
But of course, neither of them knew the answer to Zach's question, so they had no idea how many familiars they would be able to summon in the future. For now, they knew that Zach could summon his second familiar as soon as he reached level ten.
Assuming that was the only requirement, it still didn't mean that it would be every ten levels. It could be an incremental level difference between each summon. And if it were every ten levels, it would still be difficult to summon more familiars since it got harder and harder to level up.
