Lantern Scout

Oracle Text

Rally — Whenever Lantern Scout or another Ally enters the battlefield under your control, creatures you control gain lifelink until end of turn.

Card Rulings

8/25/2015 multiple instances of lifelink on the same creature are redundant. There usually isn’t much benefit in having the rally ability resolve more than once in a turn, other than that new creatures will be affected by the ability resolving an additional time.
8/25/2015 When an Ally enters the battlefield under your control, each rally ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one to resolve.
8/25/2015 If a creature with a rally ability enters the battlefield under your control at the same time as other Allies, that ability will trigger once for each of those creatures and once for the creature with the ability itself.