If he upgraded the level 2 [Combo strike] to level 3, Lucas knew that he could kill the even high-level rank 5 spirit beasts as long as he didn't mess up his streak.
However, the streak would be easily messed up because a high-level rank 5 spirit beast's speed was not something he could match.
So, before he could increase his streak to give a deadly blow to the high-level rank 5 spirit beast, he would be killed by it.
Another drawback with this skill was that he could only fight a single rank 5 spirit beast at a time and if he was surrounded by multiple rank 5 spirit beasts, he would die even before using any of his skills.
'However, the [Lynx master] skill will be different as I could use the dozen lynxes under my care to fight multiple rank 5 spirit beasts even if none of the lynxes has a rank 5 strength.'
