Mafiastyle said:
Final Fantasy XIII Summons - didn't use them at all because it seemed like bosses/monsters were never that dire to actually go for it.
Have you fought an Adamantoise yet? (Not Adamanchelid).
Summon to knock down, then spam death.
The alternative is um, near impossible unless your characters are god like (attack each leg until they die - Enemy hits for about 10,000dmg every few seconds while legs are "alive", then attack head until the Adamantoise gets up. Rinse repeat.)
FFXII, FFVIII, FFVI summons are WAY more useless (like in never used them once, for anything).