Planeswalkers as creatures

[rarehuntertay]

What happens with walkers that have been made into creature via  {Memnarch} and  {Karn, Silver Golem}? For this Example, we'll use  {Karn Liberated} with 10 loyalty counters.
1- once animated,  {Karn Liberated} is a 7/7 artifact creature with 10 counters. If he takes damage, do we both remove loyalty counters from it and mark damage on him? What amount of damage would it take to kill it?
2- Same situation, only this time it has 3 loyalty counters. How much damage is required to kill it?

[Remillo]

What happens with walkers that have been made into creature via  {Memnarch} and  {Karn, Silver Golem}? For this Example, we'll use  {Karn Liberated} with 10 loyalty counters.
1- once animated,  {Karn Liberated} is a 7/7 artifact creature with 10 counters. If he takes damage, do we both remove loyalty counters from it and mark damage on him? What amount of damage would it take to kill it?
2- Same situation, only this time it has 3 loyalty counters. How much damage is required to kill it?

When it becomes an Artifact Creature, it doesn't lose the Planeswalker typing, meaning it's still subject to losing counters when it takes damage.  You'll both mark damage and remove counters.  If your Karn is a 7/7 with 10 counters and takes 5, you'll remove 5 counters and mark 5 damage.  In the second situation, if your Planeswalker Creature is a 100/100 with 3 counters and takes 3 damage, you'll remove all three counters, and it'll be put into your graveyard the next time state-based actions are checked.

Note on cards like {Gideon Jura}, it reminds you he's still a Planeswalker and also gives him a prevention effect to prevent damage dealt to him, making it so he wont lose loyalty counters.  If an effect like {Leyline of Punishment} is there, the damage will still happen and he'll still lose counters.  Now, note on {Sarkhan the Dragonspeaker}, it reminds you that he stops being a Planeswalker while he's a Dragon and that he wont lose loyalty counters while taking damage because of this.