Sentinel

{0}: Change this creature's base toughness to 1 plus the power of target creature blocking or blocked by this creature. (This effect lasts indefinitely.)

Chronicles Foreign Black Border

Chronicles

When Sentinel comes into play, its toughness is equal to 1.
o0: Change Sentinel's toughness to 1 plus the power of target creature blocking or blocked by Sentinel.

Legends

The * in the lower right hand corner is 1 when cast. While blocking, you may choose to change * to equal one plus the power of target creature sentinel blocks this turn. While attacking, you may choose to change * to equal one plus the power of target creature that blocks Sentinel this turn.

You apply power/toughness changing effects in a series of sublayers in the following order: (a) effects from characteristic-defining abilities; (b) effects that set power and/or toughness to a specific number or value; (c) effects that modify power and/or toughness but don’t set power and/or toughness to a specific number or value; (d) changes from counters; (e) effects that switch a creature’s power and toughness. This card’s effect is always applied in (b), which means that effects applied in sublayer (c), (d), or (e) will not be overwritten; they will be applied to the new value.