Burden of the End

The gods have seen a great cataclysm on the horizon and have tasked their martyr with protecting the world from catastrophe. The exact nature of the coming End may vary: sometimes the awakening or arrival of an evil entity, sometimes the discovery and abuse of a powerful artifact, and sometimes it is a singularly destructive event that endangers the gods themselves, but the martyr must be dedicated to give their lives to stop it. To this end, the gods imbue their martyr with ancient and powerful spells, tools once gifted only to prophets.
When the coming cataclysm threatens the world, a martyr would be ill-served to ignore their call, for the cataclysm imperils them directly, as well as the lives of their family and their companions. The life of a martyr is always forfeit, but the rest of the world can yet be saved.

BURDEN SPELLS

You gain burden spells at the martyr levels listed.
Martyr Level Spells
3rd guiding bolt, protection from evil
and good
5th blindness/deafness, darkness
9th call lightning, counterspell
13th blight, control water
17th flame strike, insect plague

CANTRIPS

Starting at 1st level, your divine mission grants you a sliver of divine magic. You learn the sacred flame and thaumaturgy cantrips, and one other cantrip of your choice from the cleric spell list. You do not lose hit points for casting these spells. Wisdom is your spellcasting modifier for these spells.

HERALD OF THE END

Also at 1st level, your magic is empowered with foreknowledge of the end times, heightening its force. When you cast a martyr spell that deals damage, you can choose to reroll all of its damage dice, and must keep the new rolls. Once you use this ability, you can’t use it again until you finish a short or long rest.

SACROSANCT SPELL

At 6th level, when you cast a spell with a casting time of 1 minute or longer or a spell that has the sole effect of restoring hit points, you lose no hit points from casting the spell, if you cast it at its lowest level. Casting the spell still counts against your total number of spell uses.

EMBRACE THE INEVITABLE

Starting at 14th level, once on each of your turns, when you cast a martyr spell of 1st level or higher which calls for a saving throw to resist its effects, you can spend additional hit points equal to half the cost of the spell to cause the creature to roll its first save against the spell with disadvantage.

HALT APOCALYPSE

By 18th level, the gods have blessed you with precious time enough to forestall catastrophe. At the end of your turn, you can choose to take another turn immediately. Once you use this ability, you can’t use it again until you finish a long rest.