Tier 1's Unrivaled Strength sets up the preferred strategy of throwing enemies with Wrecking Ball that synergizes with Earthshaker at 16. This can allow you to stun the backline.

Tier 2 Garrosh can pickup Indomitable however, it is not guaranteed to save you or be available when needed (cooldown is 40 seconds for 1.5 seconds of safety). However, In For the Kill turns an enemy minion wave into a lot of healing and gives you better sustain. Any minion that has taken at least 2 basic attacks will likely reset your Bloodthirst.

Tier 3 offers you Oppressor which is a really good option to use on the backline you have tossed to your team to reduce their basic ability damage. However, Into the Fray can allow you to save allies who would have not survived otherwise.

While Warlord's Challenge can be effective, Decimate can slow heroes which makes for a great initiator for wrecking ball or it can make your Groundbreaker connect more often due to the Movement Speed reduction from the slow. You can also use this to disengage, slowing enemies who may be chasing your allies.

Tier 5 looks at picking up Bloodcraze to get additional healing over time on your bloodthirst. This can be useful to offset burst AOE damage. Alternatively, against an AA heavy team Defensive Measures provides a useful shield.

Tier 6 looks at taking Earthshaker. Once you pick this up your focus should switch from tossing back at the starting of a team fight to tossing at. Clumping the enemy together and stunning them is a good way to start a fight, and gives you better cooldown reductions on decimate.

Tier 7 is another flexible choice you can either choose Titanic Might that allows you to clump more people together to take damage or you can choose Deadly Calm which reduces the damage targets hit can do. When this ability is paired with Oppressor you can really minimize the damage a basic ability focused Hero can do.