1. Call of the Wild
I've seen so many people avoiding this skill. Why? Because a) they hate micromanaging units, b) the summons are so weak (according to them), c) third skill is much better (yes and no..) and so on.
But good players know the importance of this skill.
- The Hawk is for surveillance.
- The Quillbeast is for slowing enemies down (has both offensive and defensive uses)
For those who hate micromanagement (maybe because they can't properly do it), I can only advice -- Practice Makes Perfect.
Anyway, with its cheap mana cost, Rexxar's summons are really something we could not pass up. When I use Rexxar, or when my team has a Rexxar, I often share units or ask the Rexxar to share units so others could avail of the Hawk's scouting powers. The Hawk can patrol the woods, rune areas and act as a very mobile observer ward. So maybe for those who can't micro well, just share units with a friend who knows how to micro, and let him use the Hawk for you.
Also, I have to stress this point. I know many players prefer Beast Rage over Summons (all players get Wild Axes, I suppose), but early game, is Rexxar really able to attack his enemy three to five times in a row to really benefit from the attack speed bonus? What then does this skill do if Rexxar doesn't get this opportunity...? NOTHING. So that's another reason why his beasts have to be learned early.
2. Wild Axes
This spell is so intuitive. A no-brainer. Many players, in fact, have already mastered how to aim this properly to hit the most creeps and enemies. But what I'd like to point out here is the spell's ability to cut through trees! Yes, you should cast Wild Axes on forested areas while awaiting an enemy push just to check if they're hiding out there, preparing an ambush. You may also use this skill to reroute creeps or awaken neutrals. The possibilities and their benefits are endless. Think outside the box!