Summoning familiars provide passive bonuses, including invisible skill boosts that increase your effective level while training. These boosts do not allow you to perform actions that require a higher level than your actual one.

Familiar Level Charm Tertiary Passive boost
Dreadfowl 4 Gold Raw chicken +1 Farming lvl
Granite crab 16 Gold Iron ore +1 Fishing lvl
Desert wyrm 18 Green Bucket of sand +1 Mining lvl
Beaver 33 Green Willow logs +2 Woodcutting lvls
Pyrelord 46 Crimson Tinderbox +3 Firemaking lvls
Ibis 56 Green Harpoon +3 Fishing lvls
Spirit graahk 57 Blue Graahk fur +5 Hunter lvls
Spirit kyatt 57 Blue Kyatt fur +5 Hunter lvls
Spirit larupia 57 Blue Larupia fur +5 Hunter lvls
Stranger plant 64 Crimson Bagged plant I +1 Farming lvl (+4% of your farming level)
Arctic bear 71 Gold Polar kebbit fur +7 Hunter lvls
Obsidian golem 73 Blue Obsidian charm +7 Mining lvls
Granite lobster 74 Crimson Granite +4 Fishing lvls
Lava titan 83 Blue Obsidian charm +10 Mining lvls
Wolpertingers 92 Crimson Raw rabbit + wolf bones +5 Hunter lvls