Stat Gambling
1. MDEF+DEF always have the same stat changes
2. MATK+ATK always have the same stat changes
3. Stat caps are based on level. For example a level 30 Angelo's HP, MATK, ATK, MDEF, DEF, and SPD caps are all thirty. While a 60 Hydra's caps are 60.
4. To get your monsters stats to the cap you shouldn't use silver. While silver is good while a monsters upgrades are low, it will almost never get a upgrade while its stats are near the cap.