strategy 1. Is to (since Magmasaurs are on lost island too) use a Sinomacrops, a high level Sinomacrops, grab the egg and fly away.

Strategy 2. If you wanna get Magmasaurs from genesis, use the HLN-A bot, when you see a nest with a egg, go a little closer to it, tell HLN-A to teleport you away and then quickly grab the egg