Shyvana is one of those champions who farm up to level 6 before ganking, but if the situation allows, you can go to the gang on your 4th level, but it is better to take the first dragon at that time by buying a control totem and be sure that the enemy forester is either on top or far away farming his forest. Sivana is a strong champion if given the opportunity to farm. It can be accelerated both with the help of farm and objects, and from the Ganges. She is weak in the early stages of the game, but very strong in the middle and late stages.
If the situation is such that there is little fat in your team, then you can buy the Randuin's Omen and Dead Man's Armor. It all depends on the situation. It deals damage as it has gathered in fat, and as a juggernaut. That's all.) Have a nice skating rink and have a good win!