Undying needs a rework...
He just doesn't scale past certain periods. He needs his situational benefits improved and his scalability. He should have a % rather than fixed damage/heal. His strength steal could also maybe be like Slarks agi steal...
He's good early then takes a dive off a cliff...
Yeah, his soul rip can deal 500 dmg/heal, but only if there's 20 enemy near. Its inconsistent, and unless there's a hero with lots of units (brood, pl) you rely pretty much on your tombstone to reach that and only to cast it at max power once if no one targets your zombies. Decay is only good early game and timbersaw's whirling death deals more damage to strength heroes at level 1.
Maybe make it less spamable by increasing the mana cost, but have a base dmg + str steal based on a % of current str.
Soul rip could have a slow added to it to make it a bit more useful, since his only other source of slows is his ult with 9% and his tombstone with 7% for each zombies which cannot go higher than 63% if no one ever targets the zombies and stays near the tombstone for the entire duration, making slows pointless if they're not running away.
Undying is awesome and really excels at early clashes and tri versus tri scenarios. He's also great in 2v3 lanes. He's an early death ball hero and I think his niche is fine.
Yeah, thats true, but he takes a support slot with basically no CC or reliable healing. He'll be great vs a trilane early, but he scales off so quickly I'm not sure he's worth taking when you have other counter trilanes heroes with better scaling and decent dmg/CC lateggame