Skills in grey are bad in my opinion.

Level 1
Block: Reverberation is strictly superior.

Infused Hammer: Muradin has minor mana problems. I suggest never using abilities on minions. Thunderclap does negligible damage anyway, and Muradin is weak during the laning phase no matter which talents are picked.

Perfect Storm: The damage stacks don't make much of a difference; it can double Storm Bolt's damage, but that still isn't much damage. Synergizes really well with Sledgehammer, though; get both of these talents, or neither.

Reverberation: Prevents a lot of damage. It's like giving Block to allies. Great talent, even when there are no right click heroes on the enemy team.

Level 4
Third Wind: This increases Second Wind's regeneration by 33%. Significant, but sustaining while in a fight is much more important.

Sledgehammer: Without this talent, Muradin does very little building damage, but that's not his job anyway. Also allows Muradin to kill Siege Giants fairly quickly. Pairs excellently with Perfect Storm, which each hero hit granting 20 more damage.

Crowd Control: You will have mana troubles with this talent. Helps Muradin clear minion waves, but at the cost of lots of mana. A not-free version of Thunderburn.

Thunderburn: Excellent talent because the second hit also applies the slow, and is affected by Reverberation and Thunder Strike. Costs no additional mana! If both pulses hit, the enemy is slowed for a total of 5 seconds, up from 2.5 for movement and 3 for attack.


Level 7
Piercing Bolt: Storm Bolt is ineffective without this talent. In team fights, this talent allows you to shut down channeling spells easily from any position. Also allows for an easier stun against minion spawning heroes, and against heroes behind structures or minions.

Landing Momentum: Dwarf Toss should be saved for escaping 75% of the time, and escaping is already easy without the movement speed boost. This talent helps with catching fleeing heroes; other than that, I see no use.

Skullcracker: The micro stun simply doesn't occur fast enough.

Battle Momentum: Great for keeping Avatar off cooldown. Allows for Thunderclap spamming, but at the cost of mana and thus sustain. Without Piercing Bolt, Thunder Bolt is a bad skill. If the other team has absolutely zero channeling heroes but lots of auto attackers, then Battle Momentum can be a wise choice.

Level 10
Avatar: Adds 40% HP at level 20. The micro stuns really slow down movement and attack speeds. Great talent, but long cooldown; sometimes may not be up during a team fight.

Haymaker: 700 damage at level 20; a decent chunk! Also stuns for about 1 second during the attack animation. Good for knocking players into your team, or for removing a hero from the fight for a few seconds. Very low cooldown, so it's always up during a team fight. However, can unclump the enemy team; this is bad if you have splash damage heroes on your team. Take care not to send vulnerable targets away from your team. Enemies can be knocked through terrain and buildings, except for the outer edges of the map; can be tricky to predict where the enemy hero will end up. Powerful skill in duels.

Level 13
Burning Rage: Adds a decent amount of damage that scales well through the game. Area of effect is suprisingly large. Good when going for lots of sustain. If you want Rewind at level 20, Thunder Strike is recommended over this.

Healing Static: Heals for 7.5% of health if 5 targets are hit. Lackluster. Second Wind already heals quickly while laning minions.

Thunder Strike: A whopping amount of damage. Very strong on maps with the least team fighting. Best choice if Rewind is taken at level 20. Weak against any hero that summons minions.

Spell Shield: More useful now that Jaina and Kaelthas are ubiquitous. However, I'm not a fan of this talent because without Burning Rage or Thunder Strike, Muradin deals so little damage that he can be ignored during team fights.

Level 16
Dwarf Launch: The talent of choice for those that like to go deep, and then deeper still.

Heavy Impact: Another stun is powerful, but Dwarf Toss is essential for escaping.

Give 'Em The Axe!: Muradin's auto attacks don't actually do any damage, and 0 x 175% is still 0.

Imposing Presence: A good talent, but if Reverberation is chosen at level 1, this talent becomes redundant.

Stoneform: Provides more HP than Avatar. If used while in Avatar form, Stoneform provides even more HP! This talent by far outshines anything else in this tier.

Level 20
Unstoppable Force: If CC is a problem, this talent will help tremendously during team fights. The 30% extra duration is useful mostly for dishing out more auto attack stuns.

Grand Slam: You can hold 2 charges, but the skill still only adds 1 charge every 40 seconds. The other choices in this tier are much more powerful.

Hardened Shield: A great choice if the other team is very bursty, even if Avatar was chosen earlier.

Rewind: Pairs excellently with Thunder Strike for big burst damage and double stun. Combo can be Dwarf Toss > Storm Bolt > Thunderclap > Rewind > Storm Bolt > Thunderclap > Dwarf Toss. Haymaker at any point for added awesome. You will need at least 33% of your mana for Rewind to be useful.

Most sustain and CC
Stick on to the enemy team's damage dealers. You can sustain long enough to prevent a lot of damage.

Dueler
Great on maps with little team fighting, such as Dragon Shire. The burst from Haymaker and Thunder Strike catches a lot of people off guard. Reverberation allows you to trade auto attacks efficiently. Haymaker is good for setting up plays, similar to Diablo.

Variations
There are a few powerful synergies in Muradin's talent tree. It is viable to combine these pairs with any build.

Reverberation(1) + Thunder Burn(4)
Perfect Storm(1) + Sledgehammer(4)
Thunder Strike(13) + Rewind(20)