Ignition Phase (イグニッションフェイズ Igunisshon Feizu) is the fourth phase of a turn after Resource Phase and also the last phase before Main Phase.
During this phase, the turn player may choose to perform Ignition or skip to the Main Phase. Certain Z/X has automatic abilities and effects that either has the timing of "at the beginning of the Ignition Phase" or only triggered if said Z/X appeared during Ignition Phase.
Comprehensive Rules
505 Ignition Phase
505.1 "At the beginning of the Ignition Phase" automatic occurence activates.
505.2 Perform the priority preprocessing (702).
505.3 The turn player is able to choose a card in their own Charge, or choose to pass.
505.3a If the turn player choose a card in Charge, they move that card into their own Trash, and then reveal the topmost card of their own Deck Zone. If that card is a card with Ignition Icon, the turn player is able to play (803) that card immediately without paying the Cost of that card. If that card is not played, or is a card without Ignition Icon, put that card into Trash.
505.4 Perform the priority preprocessing (702).
505.5 If the turn player chooses a card in Charge, return to 505.3. If the turn player choose to pass, proceed to the Main Phase.
