Form of the Dragon
Enchantment
At the beginning of your upkeep, this enchantment deals 5 damage to any target.
At the beginning of each end step, your life total becomes 5.
Creatures without flying can't attack you.
Carl Critchlow
The List (PLST)
• #9ED-187Rulings
Unless some effect explicitly says otherwise, a creature that can’t attack you can still attack a planeswalker you control.
(wotc • 2014-02-01)
It sets your life total at the beginning of the end step of every player’s turn, not just your own.
(wotc • 2004-10-04)
If you life total was above 5 at end of turn, then you lose life to make your total 5. If it was less than 5, you gain life to bring it to 5.
(wotc • 2004-10-04)
Rulings
Unless some effect explicitly says otherwise, a creature that can’t attack you can still attack a planeswalker you control.
(wotc • 2014-02-01)
It sets your life total at the beginning of the end step of every player’s turn, not just your own.
(wotc • 2004-10-04)
If you life total was above 5 at end of turn, then you lose life to make your total 5. If it was less than 5, you gain life to bring it to 5.
(wotc • 2004-10-04)