Undying

Catch both opponents on the lane with Decay and use the extra damage to harass or secure last hits.

Check for the number of stick charges opponents have before diving or committing for a kill.

Don't make it too easy for opponents to destroy Tombstone. Place it on pillars, cliffs and protect it.

Tombstone destroys trees and provides great vision.

When you drop low on resources consider suiciding into neutral camp or opponents towers to reset quickly.

Hit an opponent your cores are targeting at least once for damage amplification while in Flesh Golem form.

Undying allows the team to kill Roshan early due to zombie tanking and damage amplification from Flesh Golem.

Undying uses Decay frequently. Magic Stick and Wand will be charged up.

Keep distance from Undying as he is likely to have high damage due to Decay stacks.

Keep an eye on your total HP against Decay spam. Soul Rip can finish you off.

Focus Tombstone in fights or you risk being slowed greatly and take a lot of damage.

Consider killing off zombies chasing you or team mates in trouble.

Avoid being hit by Undying in Flesh Golem form as you will take extra damage and be slowed.