Life Link (Su)
Whenever the eidolon takes enough damage to send it back to its home plane, the summoner can, as a free action, sacrifice any number of hit points. Each hit point sacrificed in this way prevents 1 point of damage done to the eidolon. This can prevent the eidolon from being sent back to its home plane.
In addition, the eidolon and the summoner must remain within 100 feet of one another for the eidolon to remain at full strength. If the eidolon is beyond 100 feet but closer than 1,000 feet, its current and maximum hit point totals are reduced by 50%. If the eidolon is more than 1,000 feet away but closer than 10,000 feet, its current and maximum hit point totals are reduced by 75%. If the eidolon is more than 10,000 feet away, it is immediately returned to its home plane. Current hit points lost in this way are not restored when the eidolon gets closer to its summoner, but its maximum hit point total does return to normal.
Summon Monster II (Sp)
7 times/day, Duration: 3 rounds
Bond Senses (Su)
A summoner can, as a standard action, share the senses of his eidolon, hearing, seeing, smelling, tasting, and touching everything the eidolon does. He can use this ability a number of rounds per day equal to his summoner level. There is no range to this effect, but the eidolon and the summoner must be on the same plane. The summoner can end this effect as a free action.