Bella, demon devourer

Flash. When Bella enters the battlefield creatures you control gain first strike and destroy all creatures your opponents control with power or toughness 2 or less and first strike.
{t}{5}{x}: Destroy X demons.
{1}{w}: Creatures you control get +1/+1 until end of turn.
{1}{u}: Creatures your opponents control get-1/-1 until end of turn.