Guard Dog 2W
Creature - Hound
Sustain - If you lost no life last turn, ~ enters the battlefield with two +1/+1 counters on it.

Siege Rations 0
Sustain - At the beginning of your upkeep, if you lost no life last turn, put a charge counter on ~.
T, Remove a charge counter from ~: You gain 1 life.

Merciful Reckoning 3WW
Destroy all creatures.
Sustain - If you lose no life last turn, instead choose a creature you control, then destroy all other creatures.