When Rosie Cotton of South Lane enters and creates a Food token, that token creation triggers Rosie Cotton’s “Whenever you create a token” ability, which can put a +1/+1 counter on Herd Baloth; placing that +1/+1 counter on Herd Baloth then triggers Herd Baloth’s ability to (optionally) create a 4/4 Beast token, and creating that Beast token will in turn trigger Rosie Cotton again — producing a repeatable chain of triggers. This interaction uses token creation and counter placement rules , counter rules , and normal handling of triggered abilities and the stack .
Step 1
Rosie Cotton of South Lane enters the battlefield; its triggered ability “When Rosie Cotton enters, create a Food token” will trigger and, when it resolves, creates a Food token (this is token creation under ).
Step 2
The act of creating that Food token causes Rosie Cotton’s other triggered ability “Whenever you create a token, put a +1/+1 counter on target creature you control other than Rosie Cotton” to trigger (see and Ruling [2023-06-16] regarding targeting creature tokens).
Step 3
When Rosie’s token-created trigger resolves, it puts a +1/+1 counter on a legal target (for example Herd Baloth) — placing that counter is governed by the counters rules .
Step 4
Placing one or more +1/+1 counters on Herd Baloth causes Herd Baloth’s triggered ability (“Whenever one or more +1/+1 counters are put on this creature, you may create a 4/4 green Beast creature token”) to trigger; that triggered ability is optional (you may choose whether to create the Beast) and goes on the stack .
Step 5
If you choose to create the 4/4 Beast when Herd Baloth’s ability resolves, that creation is a token creation event under , which then triggers Rosie Cotton’s “Whenever you create a token” ability again, and the whole sequence repeats.
Step 6
Because Herd Baloth’s token creation is optional, you can stop repeating the loop by choosing not to create the Beast when its ability resolves; otherwise you can repeat the cycle multiple times, each time generating a +1/+1 counter and a new Beast token (each event creates separate triggered abilities that are placed on the stack ).
Resolution
Rosie Cotton’s Food creation triggers Rosie’s token-created trigger, which can put a +1/+1 counter on Herd Baloth; when that counter is put on Herd Baloth its ability may create a 4/4 Beast token, which then triggers Rosie again. You can repeat this sequence as many times as you want (or stop at any time) because Herd Baloth’s token creation is optional (“you may”), and each creation/placement is a separate event that creates separate triggered abilities to be put on the stack , , .
